Looking at the diagram, work out the angle of a) x, b) y, and c) z

a) the triangle is isosceles so the two missing angles must be identical. all angles in a triangle add up to 180. therefore, 180-40=140 140/2 = 70* = xb) this triangle has two angles given already, so the same rule applies. 90 + 40 = 130 180-130 = 50 = yc) now you know two out of three angles on the straight line. the angles at a point on a straight line all add up to 180. therefore, x + y + z = 180. 70+50+z=180. 120+z=180. z = 60.