PSLE The perimeter of figure ABCDE is (10
k + 21) cm. The perimeter of square ABCD is 20 cm.
- Find the perimeter of triangle ADE in terms of k.
- The perimeter of figure ABCDE is 111 cm. What is the value of k? Give your answer in cm.
(a)
Length of the square
= 20 ÷ 4
= 5 cm
Total lengths of AB, BC and CD
= 3 x 5
= 15 cm
Perimeter of triangle ADE
= 10
k + 21 - 5 - 5
= (10
k + 11) cm
(b)
10
k + 21 = 111
10
k = 111 - 21
10
k = 90
k = 90 ÷ 10 = 9
Value of
k = 9 cm
Answer(s): (a) (10
k + 11) cm; (b) 9 cm