Exercise 2 Page 573

If two figures are similar by a scale factor, then the perimeter of one figure is equal to the perimeter of the other figure multiplied by the scale factor.

about 14.6inches

Practice makes perfect

We are given a pair of similar triangles, the lengths of two of their corresponding sides, and the perimeter of one of the triangles.

First, let's assign labels to the vertices of the given triangles.

Since △ MNO and △ QRS are similar, the perimeter of △ QRS is equal to the perimeter of △ MNO multiplied by the scale factor. Therefore, to find the unknown perimeter we first need to find the scale factor which is the quotient of the two corresponding side lengths. Scale Factor [0.5em] RS/NO substitute ⟶ 6.3/8.4= 3/4 Finally, the perimeter of △ QRS is equal to 19.4 times 34.

P_(△ QRS)= 19.4 ( 3/4)

MoveLeftFacToNum

a*b/c= a* b/c

P_(△ QRS)=58.2/4

CalcQuot

Calculate quotient

P_(△ QRS)=14.55

RoundDec

Round to 1 decimal place(s)

P_(△ QRS)≈14.6

The perimeter of △ QRS is about 14.6 inches.