PSLE The perimeter of figure CDEFG is (8
r + 21) cm. The perimeter of square CDEF is 16 cm.
- Find the perimeter of triangle CFG in terms of r.
- The perimeter of figure CDEFG is 61 cm. What is the value of r? Give your answer in cm.
(a)
Length of the square
= 16 ÷ 4
= 4 cm
Total lengths of CD, DE and EF
= 3 x 4
= 12 cm
Perimeter of triangle CFG
= 8
r + 21 - 4 - 4
= (8
r + 13) cm
(b)
8
r + 21 = 61
8
r = 61 - 21
8
r = 40
r = 40 ÷ 8 = 5
Value of
r = 5 cm
Answer(s): (a) (8
r + 13) cm; (b) 5 cm