The perimeter of ∆PQR is 45, PQ = 15, ∆PQR ∼∆STU, and ST = 25. What is the perimeter of ∆STU? a. 25.3 b. 75 c. 8.3 d. 37.5

Answer 1

Jay,

We are given that the two triangles are similar. That means they have all the same angles, and their side lengths are proportionate to each other.

All we have to do here is figure out what the ratio is between the side lengths of triangle PQR and the side lengths of triangle STU.

Since PQ is 15 and ST is 25, we know that the proportion between the triangles' side lengths is 25/15, or 5/3.

The respective perimeters of the two triangles are naturally in the same proportions. So we can take the perimeter of triangle PQR and multiply it by 5/3 to get the perimeter of triangle STU, which is 75.

Hope this helps! :)

Answer 2

25/15 = 5/3 = x/45

5 =x/15

x=75

B is correct