Question

What is EC if AC = 12, BC = 5, and DC = 4?

A. 30
B. 9
C. 15
D. 7

Answer 1

we need to find ED first

the formula for this would be (AB +BC)*BC = (ED+DC)*DC

lets replace the letters with the given numbers:

If AC = 12 and BC = 5 then AB = 12-5 = 7

so we get:
(7+5) *5 = (ED+4)*4

12*5 = (ED+4)*4

60 = (ED+4)*4

60/4 = (ED+4)

15 = ED +4

ED = 15-4 = 11

now add ED + DC to get EC

11+4 = 15
 The answer is C. 15