An arc of 30 ° in one circle is double an arc in a second circle, the radius of which is three times the radius of the first. Then the angles subtended by the arc of the second circle at its center is 

The exterior angle of a regular polygon is one-third of its interior angle, the number of sides of the polygon is -

The area of a circle is proportional to the square of its radius. A small circle of radius 3 cm is drawn within a larger circle of radius 5 cm. Find the ratio of the difference between the area of the larger circle and that of the smaller circle to the area of the larger circle.

In a polygon, the sum of the interior angles is double the sum of the exterior angles. What is the number of sides of the polygon?

If the circumradius of an equilateral triangle ABC is 8 cm, then what is the height of the triangle?

The length of a chord which is at a distance of 12 cm from the center of a circle of radius 13 cm is 

If ABC is an equilateral triangle and P, Q, R respectively denote the middle points of AB, BC, CA, then 

The length of the common chord of two circles of radii 30 cm and 40 cm whose centers are 50 cm apart is (in cm)