4. Two circles with centres P and Q touch each other externally. A straight line drawn through the point of contact intersects the circle with centre P at A and the circle with centre Q at B. Then, which of the following is true?
5. The height of a right circular cylinder is twice its radius of the base. If its height be 6 times its radius of the base, then the volume of the cylinder will be 539 cub.cm more. Assuming ? = 22/7, the height of the cylinder is
7. A chord of a circle is equal to its radius. A tangent is drawn to the circle at an extremity of the chord. The angle between the tangent and the chord is