Equations: y = x+4 and x^2 +y^2 -8x +4y = 30
It appears that the given line is a tangent line to the given circle and the point of contact works out as (-1, 3)
It is a right angle
If y = 2x+1 is a tangent line to the circle 5y^2 +5x^2 = 1 then the point of contact is at (-2/5, 1/5) because it has equal roots
The tangent of a circle is perpendicular to the radius to the point of contact (Xc, Yc).The point (-2, 3), the centre of the circle (Xo, Yo) and the point of contact of the tangent (Xc, Yc) form a right angle triangle.The leg from the point (-2, 3) to the point of contact (Xc, Yc) is the required lengthThe leg from the centre of the circle (Xo, Yo) to the point of contact (Xc, Yc) has length equal to the radius (r) of the circleThe hypotenuse is the length between the point (-2, 3) and the centre of the circle (Xo, Yo).To solve this:Find the centre (Xo, Yo) of the circle, and its radius r.Use Pythagoras to find the length between the point (-2, 3) and the centre of the circle (Xo, Yo)Use Pythagoras to find the length between the point (-2, 3) and the point of contact (Xc, Yc) of the tangent - the required length.Hint: a circle with centre (Xo, Yo) and radius r has an equation of the form:(x - Xo)² + (y - Yo)² = r²Have a go at solving it now you know how, before reading the solution below:------------------------------------------------------------------------------Circle:x² + y² + 6x + 10y - 2 = 0→ x² + 6x + y² + 10y - 2 = 0→ (x + (6/2))² - (6/2)² + (y + (10/2))² - (10/2)² - 2 = 0→ (x + 3)² - 9 + (y + 5)² - 25 - 2 = 0→ (x + 3)² + (y + 5)² = 36 = 6²→ Circle has centre (-3, -5) and radius 6Line from centre of circle (-3, -5) to the given point (-2, 3):Using Pythagoras to find length of a line between two points (x1, y1) and (x2, y2):length = √((x2 - x1)² + (y2 - y1)²)To find length between given point (-2, 3) and centre of circle (-3, -5)→ length = √((-5 - -2)² + (-3 - -3)²)= √((-3)² + (-6)²)= √45Tangent line segment:Using Pythagoras to find length of tangent between point (-2, 3) and its point of contact with the circle:centre_to_point² = tangent² + radius²→ tangent = √(centre_to_point² - radius²)= √((√45)² + 6²)= √(45 + 36)= √81= 9The length is 9 units.
The tangent of a circle is perpendicular to the radius to the point of contact (Xc, Yc).The point (Xg, Yg), the centre of the circle (Xo, Yo) and the point of contact of the tangent (Xc, Yc) form a right angle triangle.The leg from the point (Xg, Yg) to the point of contact (Xc, Yc) is the required lengthThe leg from the centre of the circle (Xo, Yo) to the point of contact (Xc, Yc) has length equal to the radius (r) of the circleThe hypotenuse is the length between the point (0, 0) and the centre of the circle (Xo, Yo).To solve this:Find the centre (Xo, Yo) of the circle, and its radius r;Use Pythagoras to find the length between the point (Xg, Yg) and the centre of the circle (Xo, Yo);Use Pythagoras to find the length between the point (Xg, Yg) and the point of contact (Xc, Yc) of the tangent - the required length.Hint: a circle with centre (Xo, Yo) and radius r has an equation of the form:(x - Xo)² + (y - Yo)² = r²Have a go at solving it now you know how, before reading the solution below:------------------------------------------------------------------------------Circle:x² + y² - 4x - 8y - 5 = 0→ x² - 4x + y² - 8y - 5 = 0→ (x - (4/2))² - (4/2)² + (y - (8/2))² - (8/2)² - 5= 0→ (x - 2)² - 4 + (y - 4)² - 16 - 5 = 0→ (x - 2)² + (y - 4)² = 25 = radius²→ Circle has centre (2, 4) and radius √25 = 5Line from centre of circle (2, 4) to the given point (8, 2):Using Pythagoras to find length of a line between two points (x1, y1) and (x2, y2):length = √((x2 - x1)² + (y2 - y1)²)To find length between given point (8, 2) and centre of circle (2, 4)→ length = √((2 - 8)² + (4 - 2)²)= √((-6)² + 2²)= √40Tangent line segment:Using Pythagoras to find length of tangent between point (8, 2) and its point of contact with the circle:centre_to_point² = tangent² + radius²→ tangent = √(centre_to_point² - radius²)= √((√40)² + 25)= √65≈ 8.06
Suppose the circle meets QR at A, RP at B and PQ at C. PQ = PR (given) so PC + CQ = PB + BR. But PC and PB are tangents to the circle from point P, so PC = PB. Therefore CQ = BR Now CQ and AQ are tangents to the circle from point Q, so CQ = AQ and BR and AR are tangents to the circle from point R, so BR = AR Therefore AQ = AR, that is, A is the midpoint of QR.
It is a right angle
The radius is the distance between the center of a circle and a point on the circle
Definition: a tangent is a line that intersects a circle at exactly one point, the point of intersection is the point of contact or the point of tangency. a tangent is a line that intersects a circle at exactly one point, the point of intersection is the (point of contact) or the **point of tangency**.
If y = 2x+1 is a tangent line to the circle 5y^2 +5x^2 = 1 then the point of contact is at (-2/5, 1/5) because it has equal roots
It works out that the tangent line of y -3x -5 = 0 makes contact with the circle x^2 +y^2 -2x +4y -5 = 0 at the coordinate of (-2, -1) on the coordinated grid.
It works out that the tangent line of y -3x -5 = 0 makes contact with the circle of x^2 + y^2 -2x +4y -5 = 0 at (-2, -1)
The tangent of a circle is perpendicular to the radius to the point of contact (Xc, Yc).The point (-2, 3), the centre of the circle (Xo, Yo) and the point of contact of the tangent (Xc, Yc) form a right angle triangle.The leg from the point (-2, 3) to the point of contact (Xc, Yc) is the required lengthThe leg from the centre of the circle (Xo, Yo) to the point of contact (Xc, Yc) has length equal to the radius (r) of the circleThe hypotenuse is the length between the point (-2, 3) and the centre of the circle (Xo, Yo).To solve this:Find the centre (Xo, Yo) of the circle, and its radius r.Use Pythagoras to find the length between the point (-2, 3) and the centre of the circle (Xo, Yo)Use Pythagoras to find the length between the point (-2, 3) and the point of contact (Xc, Yc) of the tangent - the required length.Hint: a circle with centre (Xo, Yo) and radius r has an equation of the form:(x - Xo)² + (y - Yo)² = r²Have a go at solving it now you know how, before reading the solution below:------------------------------------------------------------------------------Circle:x² + y² + 6x + 10y - 2 = 0→ x² + 6x + y² + 10y - 2 = 0→ (x + (6/2))² - (6/2)² + (y + (10/2))² - (10/2)² - 2 = 0→ (x + 3)² - 9 + (y + 5)² - 25 - 2 = 0→ (x + 3)² + (y + 5)² = 36 = 6²→ Circle has centre (-3, -5) and radius 6Line from centre of circle (-3, -5) to the given point (-2, 3):Using Pythagoras to find length of a line between two points (x1, y1) and (x2, y2):length = √((x2 - x1)² + (y2 - y1)²)To find length between given point (-2, 3) and centre of circle (-3, -5)→ length = √((-5 - -2)² + (-3 - -3)²)= √((-3)² + (-6)²)= √45Tangent line segment:Using Pythagoras to find length of tangent between point (-2, 3) and its point of contact with the circle:centre_to_point² = tangent² + radius²→ tangent = √(centre_to_point² - radius²)= √((√45)² + 6²)= √(45 + 36)= √81= 9The length is 9 units.
The tangent of a circle is perpendicular to the radius to the point of contact (Xc, Yc).The point (Xg, Yg), the centre of the circle (Xo, Yo) and the point of contact of the tangent (Xc, Yc) form a right angle triangle.The leg from the point (Xg, Yg) to the point of contact (Xc, Yc) is the required lengthThe leg from the centre of the circle (Xo, Yo) to the point of contact (Xc, Yc) has length equal to the radius (r) of the circleThe hypotenuse is the length between the point (0, 0) and the centre of the circle (Xo, Yo).To solve this:Find the centre (Xo, Yo) of the circle, and its radius r;Use Pythagoras to find the length between the point (Xg, Yg) and the centre of the circle (Xo, Yo);Use Pythagoras to find the length between the point (Xg, Yg) and the point of contact (Xc, Yc) of the tangent - the required length.Hint: a circle with centre (Xo, Yo) and radius r has an equation of the form:(x - Xo)² + (y - Yo)² = r²Have a go at solving it now you know how, before reading the solution below:------------------------------------------------------------------------------Circle:x² + y² - 4x - 8y - 5 = 0→ x² - 4x + y² - 8y - 5 = 0→ (x - (4/2))² - (4/2)² + (y - (8/2))² - (8/2)² - 5= 0→ (x - 2)² - 4 + (y - 4)² - 16 - 5 = 0→ (x - 2)² + (y - 4)² = 25 = radius²→ Circle has centre (2, 4) and radius √25 = 5Line from centre of circle (2, 4) to the given point (8, 2):Using Pythagoras to find length of a line between two points (x1, y1) and (x2, y2):length = √((x2 - x1)² + (y2 - y1)²)To find length between given point (8, 2) and centre of circle (2, 4)→ length = √((2 - 8)² + (4 - 2)²)= √((-6)² + 2²)= √40Tangent line segment:Using Pythagoras to find length of tangent between point (8, 2) and its point of contact with the circle:centre_to_point² = tangent² + radius²→ tangent = √(centre_to_point² - radius²)= √((√40)² + 25)= √65≈ 8.06
Suppose the circle meets QR at A, RP at B and PQ at C. PQ = PR (given) so PC + CQ = PB + BR. But PC and PB are tangents to the circle from point P, so PC = PB. Therefore CQ = BR Now CQ and AQ are tangents to the circle from point Q, so CQ = AQ and BR and AR are tangents to the circle from point R, so BR = AR Therefore AQ = AR, that is, A is the midpoint of QR.
The tangent of a circle is perpendicular to the radius to the point of contact (Xc, Yc).The point (0, 0), the centre of the circle (Xo, Yo) and the point of contact of the tangent (Xc, Yc) form a right angle triangle.The leg from the point (0, 0) to the point of contact (Xc, Yc) is the required lengthThe leg from the centre of the circle (Xo, Yo) to the point of contact (Xc, Yc) has length equal to the radius (r) of the circleThe hypotenuse is the length between the point (0, 0) and the centre of the circle (Xo, Yo).To solve this:Find the centre (Xo, Yo) of the circle, and its radius r.Use Pythagoras to find the length between the point (0, 0) and the centre of the circle (Xo, Yo)Use Pythagoras to find the length between the point (0, 0) and the point of contact (Xc, Yc) of the tangent - the required length.Hint: a circle with centre (Xo, Yo) and radius r has an equation of the form:(x - Xo)² + (y - Yo)² = r²Have a go at solving it now you know how, before reading the solution below:------------------------------------------------------------------------------Circle:x² + y² + 4x - 6y + 10 = 0→ x² + 4x + y² - 6y + 10 = 0→ (x + (4/2))² - (4/2)² + (y + (-6/2))² - (-6/2)² +10 = 0→ (x + 2)² - 4 + (y - 3)² - 9 + 10 = 0→ (x + 2)² + (y - 3)² = 3 = radius²→ Circle has centre (-2, 3) and radius √3Line from centre of circle (-2, 3) to the given point (0, 0):Using Pythagoras to find length of a line between two points (x1, y1) and (x2, y2):length = √((x2 - x1)² + (y2 - y1)²)To find length between given point (0, 0) and centre of circle (-2, 3)→ length = √((0 - -2)² + (0 - 3)²)= √(2² + (-3)²)= √13Tangent line segment:Using Pythagoras to find length of tangent between point (0, 0) and its point of contact with the circle:centre_to_point² = tangent² + radius²→ tangent = √(centre_to_point² - radius²)= √((√13)² + (√3)²)= √(13 + 3)= √16= 4
A line tyhat's tangent to a circle intersects the circle in exactly one single point. The radius drawn to that point is perpendicular to the tangent.
Since AB and AC are tangent to the circle O, it seems that they both are drawn from the same outside point A. As tangents to a circle from an outside point are congruent, AB ≅ BC. Also, a tangent is perpendicular to radius drawn to point of contact. So that OB and OC are congruent radii. Therefore, the perimeter of the quadrilateral ABOC equals to P = 2(12 cm) + 2(5 cm) = 34 cm.