Two parallel sides DC & AB of a trapezium are 12 cm & 36 cm respectively. If the non-parallel sides are each equal to 15 cm, how do I find the area of the trapezium?
The shorter base, from D to C, is 12 cm long. The distance between the bases of those two perpendiculars (lets call them E and F) is also 12 cm. That means the two pieces outside E and F total 36- 12= 24 cm. And looking at the right triangles formed at the ends by those perpendicular, "HL" tells you the two pieces are each length 12. Now, use the Pythagorean theorem.