Question

The three sides of a triangle are in different colors – blue, green and red. The ratio of the length of the blue side to the length of the green side to the length of the red side is 3 : 4 : 5. The perimeter of the triangle is 240 cm. a) Fill in the blank: ___ units = 240 cm b) Fill in the blank: 1 unit = ___ cm c) What is the length of the red side of the triangle?

Answer 1

The perimeter is the distance around the triangle. Given the ratio, the perimeter using the ratio is;

= 3 + 4 + 5

= 12 units

a. 12 units = 240 cm

The perimeter in centimetres is 240cm and in ratio is 12 units so they are equivalent.

b. 1 unit = 20 cm

If 12 units are to 240 cm, 1 unit is;

= 240/12

= 20 cm

c. Length of red side;

Red side has length of 5 units. 1 unit is 20 cm.

Length in cm is;

= 5 * 20

= 100 cm