PSLE The perimeter of figure ABCDE is (4
r + 10) cm. The perimeter of square ABCD is 16 cm.
- Find the perimeter of triangle ADE in terms of r.
- The perimeter of figure ABCDE is 38 cm. What is the value of r? Give your answer in cm.
(a)
Length of the square
= 16 ÷ 4
= 4 cm
Total lengths of AB, BC and CD
= 3 x 4
= 12 cm
Perimeter of triangle ADE
= 4
r + 10 - 4 - 4
= (4
r + 2) cm
(b)
4
r + 10 = 38
4
r = 38 - 10
4
r = 28
r = 28 ÷ 4 = 7
Value of
r = 7 cm
Answer(s): (a) (4
r + 2) cm; (b) 7 cm