The area of a triangle is 15 square inches. the triangle's height is 5 inches. what is the length of the base?

*keep in mind that area of a triangle is: A= b*h/2

we know that the area is 15 inches, and the height is 5 inches

A=15
H=5

15 doubled is 30, so we know that before we divided is, it was 30

so - 5*___=30 - to figure this out we need to do the opposite of multiplying, which is dividing 

so - 30/5=6

the base is 6, to check our answer, we do this:
H=5       b*h/2
B=6           

b*h/2 = 5*6/2=15

i hope this helped!!

Iwould say they are complementary because that’s the division of a 90 degree angle and it’s split between the middle of them