A quadrilateral's four angles add up to 360°, not 180° — a quadrilateral is two triangles, so it is 180 × 2. The special quadrilaterals give you shortcuts on top of that: in a parallelogram and a rhombus, opposite angles are equal and neighbouring angles add to 180°. In the hardest questions a triangle and a quadrilateral share an angle, so the angle you find first is the one that unlocks the second shape.
Sign up free to see the worked example
A free parent account opens every Learn lesson, with worked examples, plus free practice in every topic and Test 1 of every skill. No card needed, and nothing expires.
Create a free account or sign in