And if angles 𝑥, 𝑦 and 𝑐 equal 180 ... 225 + 135 = 360 The sum of interior angles in a triangle is 180˚. In an equilateral triangle, all three angles are equal to 60˚.

Students may notice symmetry in the isosceles and equilateral triangles and non-symmetry in the scalene triangles Informal recognition of these properties may be helpful in recognizing formal ...