# Triangles

For any triangle the 3 angles add up to $$180^\circ$$

$x^\circ = 180^\circ - (70^\circ + 50^\circ )$

$= 180^\circ - 120^\circ = 60^\circ$

## Equilateral triangle

An equilateral triangle is one with all 3 sides equal in length and all 3 angles equal to $$60^\circ$$

## Isosceles triangle

An isosceles triangle is one with two sides equal in length and two equal angles.

Question

In the diagram below the triangle is isosceles. What is the value of $$a^\circ$$?

$a^\circ = 180^\circ - (70^\circ + 70^\circ )$

$= 180^\circ - 140^\circ = 40^\circ$