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Here is the proof, it is done by drawing parallel lines and using the theorem that alternate interior angles of parallel lines are congruent, which is also easily proved: The Pythagorean proof is even simpler. A line parallel to the base BC is drawn through the vertex A, which gets us two pairs of alternate angles: CBA, DAB and BCA, EAC. Now, angle BAC complements, on the one hand, CBA + BCA to the sum of the angles of DABC, and, on the other, DAB + EAC to two right angles. Basically this says that because a straight line has 180 degrees on each side, and that angles B and C are both alternate interior angles to angles BAD and CAE respectively, angles B and C can both be substituted by angles BAD and CAE. Therefore, you get angle C + angle B + angle A = 180.
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Does and isocolies triangle equal 180 degrees?
Assuming the question was if an isosceles triangle have angles that add up to 180 degrees, then yes. All triangles have angles that add up to 180 degrees.
Are all triangles equal to 180 degrees?
Yes the 3 interior angles of any triangle add up to 180 degrees
What is the sum of the angles in a four sided shape?
The sum of the angles of a four sided shape is equal to 360 degrees. One way to prove this is to draw a diagonal line connecting two opposite vertices, resulting in two triangles. Since the sum of the angles of a triangle equal 180 degrees, and there are two resulting triangles, then the sum of the angles of two triangles (180 + 180) will equal 360 degrees. Frank frank253@hotmail.com
What is the polygon whose interior angles equal 180 degrees?
It is a triangle. The formula for the total of interior angles in an n-sided polygon is 180(n-2). This is 180 degrees for triangles, 360 degrees for quadrilaterals, and 540 degrees for pentagons.
Using indirect reasoning to show that a triangle cannot have two right angles?
Triangles total 180 degrees. Triangles have three angles. Two angles of 90 degrees total 180 degrees.
