Question

In trapezul ABCD, AC intersectat cu BD={O}, iar BD=28 cm. Daca CO:OA= 3:4. Cu cat este egal OB?

Answer 1

CO / OA = DO / OB = 3/ 4 
DO / OB = 3 /4 
[ DO + OB ]  / OB = [ 3+ 4 ] / 4 
DB  / OB =  7  /4 
4 · DB = 7 · OB 
4· 28 cm = 7 · OB 
OB = 4 · 28 :7 cm = 4 · 4 cm =16 cm