Web Results

www.quickanddirtytips.com/education/math/why-does-a-triangle-have-180-degrees

And our little drawing shows that the exterior angle in question is equal to the sum of the other two angles in the triangle. In other words, the other two angles in the triangle (the ones that add up to form the exterior angle) must combine with the angle in the bottom right corner to make a 180 0 angle.

www.mathsisfun.com/proof180deg.html

The top line (that touches the top of the triangle) is running parallel to the base of the triangle. So: angles A are the same ; angles B are the same ; And you can easily see that A + C + B does a complete rotation from one side of the straight line to the other, or 180°

I've drawn an arbitrary triangle right over here. And I've labeled the measures of the interior angles. The measure of this angle is x. This one's y. This one is z. And what I want to prove is that the sum of the measures of the interior angles of a triangle, that x plus y plus z is equal to 180 degrees.

In an equilateral trianger, each angle is 60 degrees. In all triangles, including equilateral triangles, all 3 angles add up to 180 degrees. (the above assumes Euclidean - flat - space.

No, because the angles of a triangle have to total 180 degrees and if there are three angles in a triangle, 90 * 3 cannot equal 180. To have three equal sides, the angles must equal 60 degrees 60 ...

en.wikipedia.org/wiki/Sum_of_angles_of_a_triangle

In several geometries, a triangle has three vertices and three sides, where three angles of a triangle are formed at each vertex by a pair of adjacent sides. In a Euclidean space, the sum of measures of these three angles of any triangle is invariably equal to the straight angle, also expressed as 180 °, π radians, two right angles, or a half ...