Ratios and proportions 4 and 5

4. The measure of two complementary angles are in the ratio 1 : 5. What are the degree measures of the two angles?

1 : 5  means there are 6 equal parts....

So...one  of them  is  (1/6) of these

So     (1/6) * 90   =   15°

And   (5/6) * 90   =  5 * 15   =  75°

5. The ratio of length to width in a rectangle is 3 to 1. If the perimeter of the rectangle is 56 feet, what is the length of the rectangle?

P  =  2 (L + W)      but  L  =  3W.....so we have...

56   =  2 ( 3W + W)     divide by 2

28  =  3W + W

28  =  4W     divide by 4

7 = W

So  L  =  3W  =  3(7)   =  21 ft