47.88 cm2
surface area of triangle times the width/height of container.
No. 1/2 base squared + height squared=side squared on an equilateral triangle.
8.7
The area of a triangle is one-half the product of the triangle's base and height. The height of an equilateral triangle is the distance from one vertex along the perpendicular bisector line of the opposite side. This line divides the equilateral triangle into two right triangles, each with a hypotenuse of 9c and a base of (9/2)c. From the Pythagorean theorem, the height must be the square root of {(9c)2 - [(9/2)c]}, and this height is the same as that of the equilateral triangle.
Height of an equilateral triangle = √3/2 x side = √3/2 x 20 = 10√3 ≈ 17.32
surface area of triangle times the width/height of container.
Surface area of a triangular pyramid: SA = 1/2 as + 3/2 sl a = altitude of the base triangle s = side of the triangle l = slant height of the pyramid.
No. 1/2 base squared + height squared=side squared on an equilateral triangle.
8.7
An equilateral triangle with a height of 20 has a base of 23.1 (23.09401), not 15. If the base is 15 then the height will be 13 (12.99038).
The surface area of the pyramid is superfluous to calculating the slant height as the slant height is the height of the triangular side of the pyramid which can be worked out using Pythagoras on the side lengths of the equilateral triangle: side² = height² + (½side)² → height² = side² - ¼side² → height² = (1 - ¼)side² → height² = ¾side² → height = (√3)/2 side → slant height = (√3)/2 × 9cm = 4.5 × √3 cm ≈ 7.8 cm. ---------------------------- However, the surface area can be used as a check: 140.4 cm² ÷ (½ × 9 cm × 7.8 cm) = 140.4 cm² ÷ 35.1 cm² = 4 So the pyramid comprises 4 equilateral triangles - one for the base and 3 for the sides; it is a tetrahedron.
The area of a triangle is one-half the product of the triangle's base and height. The height of an equilateral triangle is the distance from one vertex along the perpendicular bisector line of the opposite side. This line divides the equilateral triangle into two right triangles, each with a hypotenuse of 9c and a base of (9/2)c. From the Pythagorean theorem, the height must be the square root of {(9c)2 - [(9/2)c]}, and this height is the same as that of the equilateral triangle.
Cutting the equilateral triangle in half results in two right triangles each with a base of length x/2, and angles of 30, 60, and 90 degrees. Using the lengths of sides of a 30-60-90 triangle it can be found that the height is (x/2)√(3), which is the same as the height of the equilateral triangle.So the height of the equilateral triangle is x√(3) / 2.
2
Height of an equilateral triangle = √3 / 2 x side = (√3 / 2 ) x 3 = 2.598 cm.
Height of an equilateral triangle = √3/2 x side = √3/2 x 20 = 10√3 ≈ 17.32
Area = 1443.376 cm2