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In the Figure FD\\AC, the area of AEF = 6sq.cm. AE = 3cm,...

In the Figure FD\\AC, the area of AEF = 6sq.cm. AE = 3cm, BC = 3cm, CD = 5cm, < BCD is an obtuse angle. Find the length of BD.

In the Figure FD\\AC, the area of AEF = 6sq.cm. AE = 3cm, BC = 3cm, CD = 5cm, < BCD is an obtuse angle. Find the length of BD.

A.

33

B.

6

C.

4

D.

213

E.

45

Correct answer is D

Area of triangle AEF = 6sq. cm

area of triangle = 12bh (Line DX makes right angles with the parallel lines)

6 = 12 x 3 x h

6 = 3h

3h = 123

h = 4 = DX

From D, C x D, CX2 = 52
- 42

= 25 - 16 = 9

Cx = 3. From angle B x D, Bx = 6(i.e. 3 + 3)

BD2 = 42 + 62


= 16 + 36 = 52

BD = 4×13

= 213