Question

Can somebody help me with this​

Answer 1

Answer:

If AB and CD are perpendicular, (slope of AB) x (slope of CD) = -1

9/a = -1

a = -9

Answer 2

Answer:

-9

Step-by-step explanation:

flip and change the sign of $\frac{3}{4}$

$\frac{4}{-3}$

set equal to each other

$\frac{4}{-3}$ = $\frac{12}{a}$

cross multiply

4a = -36

divide by 4

a = -9