The triangle shown is an isosceles triangle. Isosceles triangles have two equal sides and two equal angles. When all 3 angles are added, it should have a sum of 180°. The tip of the triangle is the part of the triangle with the smallest degree/angle. So the two remaining angles are the same amount.
180°=38°+x+?
180°=38°+71°+71°
Both missing angles are the same degree, and when both are added to 38, it has a sum of 180. x is equal to 71°.
