The triangle is an isosceles triangle, which means that two angles and sides are the same. That means that other side is also 50°. All the angles in a triangle add up to 180°. Since we know two of the angles, we should know what the angle x is. We can write it as 50 °+ 50° + x = 180°. You can add 50° and 50° to get 100°. Now you have 100° + x = 180°. Subtract 100° from both sides to get x = 80°.
