Question

This is my question pls help

Answer 1

a = 15

Explanation:

Substitute b = 12 , a = 9 into the equation

12 =
`√(a^2-9^2)`

12 =
`√(a^2-81)` ← square both sides

144 = a² - 81 ( add 81 to both sides )

225 = a² ( take square root of both sides )

±
`√(225)` = a , then

a = ± 15

a > 0 , so a = 15