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
