Question

Sorry for the weird marks but please help!!​

Answer 1

C. 8 is the correct answer.

Explanation:

Let <DAB be x°

Now,

taking x as reference angle in triangle ADB,

cosx = b/h

or, cosx = 4/AB

Now,

again taking x as reference angle in triangle ACB,

cosx = b/h

or, cosx = AB/20

Now,

cosx = AB/20 = 4/AB

or, AB/20 = 4/AB

or, AB² = 80

Now,

Using pythagoras theorem in triangle ABD,

h² = p² + b²

or, AB² = BD² + AD²

or, 80 = BD² + 4²

or, 80 - 16 = BD²

so, BD² = 64

so, BD = 8