The base of a triangle is 15 cm and height is 12 cm. The height of another triangle of double the area having the base 20 cm is :  Choose one:
A) 22 cm
B) 20 cm
C) 18 cm
D) 10 cm
E) none of these

Rationale: explanation : area of triangle , a 1 = 1 / 2 ∗ base ∗ height = 1 / 2 ∗ 15 ∗ 12 = 90 cm 2 area of second triangle = 2 ∗ a 1 = 180 cm 2 1 / 2 ∗ 20 ∗ height = 180 = > height = 18 cm option c
Answer: C