PSLE The perimeter of figure CDEFG is (10
f + 21) cm. The perimeter of square CDEF is 28 cm.
- Find the perimeter of triangle CFG in terms of f.
- The perimeter of figure CDEFG is 101 cm. What is the value of f? Give your answer in cm.
(a)
Length of the square
= 28 ÷ 4
= 7 cm
Total lengths of CD, DE and EF
= 3 x 7
= 21 cm
Perimeter of triangle CFG
= 10
f + 21 - 7 - 7
= (10
f + 7) cm
(b)
10
f + 21 = 101
10
f = 101 - 21
10
f = 80
f = 80 ÷ 10 = 8
Value of
f = 8 cm
Answer(s): (a) (10
f + 7) cm; (b) 8 cm