# Thread: Enlargement and scale factor.

1. ## Enlargement and scale factor.

Sorry i dont really understand these questions, i did them but im nearly certain ive did them wrong can someone tell me the correct answers and explain please?

1. Triangle A is enlarged with a scale factor 3 into triangle B. One side of triangle B has length of 4.5cam.

a. What is the length of the corresponding side of triangle A?

One angle of triange B is 60 degrees.

b. What is the size of the corresponding angle of triangle A?

2. The rectangle ABCD is enlarged by scale factor 1/2. Find the corresponding lengths of the sides.

a. AB
b. BC

(AB = 12.6cm)
(BC = 5.4cm)

c. Find the area of ABCD.
d. Find the area of the image.

2. Originally Posted by bronaghxo
Sorry i dont really understand these questions, i did them but im nearly certain ive did them wrong can someone tell me the correct answers and explain please?

1. Triangle A is enlarged with a scale factor 3 into triangle B. One side of triangle B has length of 4.5cam.

a. What is the length of the corresponding side of triangle A?

One angle of triange B is 60 degrees.

b. What is the size of the corresponding angle of triangle A?

2. The rectangle ABCD is enlarged by scale factor 1/2. Find the corresponding lengths of the sides.

a. AB
b. BC

(AB = 12.6cm)
(BC = 5.4cm)

c. Find the area of ABCD.
d. Find the area of the image.
Hello bronaghxo,

(1) A scale factor is simply the ratio of any two corresponding sides of similar figures.

Triangle A is 1/3 times triangle B. Therefore, the scale factor is 1/3.

One side of triangle B = 4.5. The corresponding side of triangle A is 1/3 times 4.5 = 1.5.

(1.b) Corresponding angles of similar polygons are congruent. So if triangle B has a 60 degree angle, then the corresponding angle in triangle A will also be 60 degrees.

(2) The rectangle ABCD (pre-image) is REDUCED by a scale factor of 1/2.

Multiply lengths of rectangle by 1/2 to get corresponding lengths for the image.

The area of the pre-image ABCD is length X width or 12.6cm X 5.4cm.

The image A'B'C'D' is 1/4 the area of the pre-image or 6.3cm X 2.7cm.