The given known values are:
Length of 4 cm
Width is unknown
Perimeter is 34 cm
Find the dimensions of the rectangle.
Since the geometric formula for perimeter is:
P= 2 (l + w)
L = 2w – 4 cm
W =?
Derivation and solution:
34 = 2 (2w - 4) + 2w
34 = 4w – 8 + 2w
42 = 6w
42/6 = w
W = 7 cm
34 = 2l + 2(7)
34 = 2l + 14
2l = 34 – 14
2l = 20
L = 20/2
L = 10
cm