Question

If ABCD is a rectangle, find the length of each diagonal. AC=3c/9 and BD=4-c

Answer 1

So we know that the diagonals of a rectangle are equal than 

3c/9 = 4 - c 

c/3 = 4-c

c = 3(4-c)

c = 12 -3c

4c = 12 

c = 12/4 

c = 3 

so in this case the length of AC = 3*3/9 = 9/9 = 1 and the length of
BD = 4 - 3 = 1 

hope this will help you