Construct an angle of 90

1. Draw ray AP.

2. At A , make arc meeting AP at Q

3. With same radius , from Q make arc B on the drawn arc.

4. From B , makearc C  and D as shown

From A cut off arc at D.

Join AD

Justification

angle PAB is 60 degrees . Angle BAC is also 60 deg .

Angle BAD is obtained by bisecting angle BAC , and is therefore 30 deg.

Angle PAD = 60 + 30 = 90 deg