PSLE The perimeter of figure JKLMN is (5
r + 16) cm. The perimeter of square JKLM is 28 cm.
- Find the perimeter of triangle JMN in terms of r.
- The perimeter of figure JKLMN is 56 cm. What is the value of r? Give your answer in cm.
(a)
Length of the square
= 28 ÷ 4
= 7 cm
Total lengths of JK, KL and LM
= 3 x 7
= 21 cm
Perimeter of triangle JMN
= 5
r + 16 - 7 - 7
= (5
r + 2) cm
(b)
5
r + 16 = 56
5
r = 56 - 16
5
r = 40
r = 40 ÷ 5 = 8
Value of
r = 8 cm
Answer(s): (a) (5
r + 2) cm; (b) 8 cm