Step 1:

(a)

Observe the figure:

The triangle DAB is right angled triangle and DB is the hypotenuse.

Therefore, .

Step 2:

(b)

Find .

Draw an angle bisector from A.

Angle .

Therefore, .

Redraw the figure:

From the triangle ACB:

Therefore, .

Step 3:

(c)

Find .

From the triangle ACD:

Therefore .

Step 4:

Find the length of AD.

From triangle ABD: .

Therefore,

Solution:

(a) .

(b) .

(c) .

(d)