Question

How to find this? Please help me.

Answer 1

b = 9 cm

Explanation:

the area (A) of a triangle is calculated as

A =
`(1)/(2)` bh ( b is the base and h the height )

here h = 2b , then

`(1)/(2)` × b × 2b = 81

`(1)/(2)` × 2b² = 81

b² = 81 ( take square root of both sides )

b =
`√(81)` = 9 cm