Explanation:
Right triangle
A right triangle (American English) or right-angled triangle (British English) is a triangle in which one angle is a right angle (that is, a 90degree angle). (Our solved example in mathguru.com uses this concept)
The relation
between the sides and angles of a right triangle is the basis for trigonometry.
Right triangle
http://en.wikipedia.org/wiki/Right_triangle
In an isosceles triangle, two sides are equal in length. An isosceles triangle also has
two angles of the same measure; namely, the angles opposite to the two sides of
the same length; (Our solved example in mathguru.com uses this concept)
This fact is the content of the Isosceles
triangle theorem. Some mathematicians define an isosceles triangle to have
exactly two equal sides, whereas others define an isosceles triangle as one
with at least two equal sides The latter definition would make all equilateral triangles
isosceles triangles. The 45-45-90 Right Triangle, which appears in the Tetrakis
square tiling, is isosceles.
http://en.wikipedia.org/wiki/Triangle
The
above explanation is copied from Wikipedia, the free encyclopedia and is
remixed as allowed under the Creative Commons Attribution- ShareAlike 3.0 Unported License.
(Our solved example in mathguru.com also uses the below concept.This is our own explanation, it is not taken from Wikipedia.)
The sum of all the angles in a Triangle is 180(Angle Sum Property)