The sum of all interior angles of a regular polygon is twice the sum of all its exterior angles.  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.

ABC is an isosceles triangle with AB = AC. The side BA is produced to D such that AB = AD. If ∠ABC = 30°, then ∠BCD is equal to 

In ΔABC, AB = AC and ∠B = 40 °, find the value of ∠A.

ΔABC is similar to ΔDEF. Length of AB is 18 cm and  length of the corresponding side  DE is 10 cm. What is the ratio  of Perimeter of ΔABC : Perimeter of ΔDEF?

In a triangle ΔABC, the sides DE parallel to BC and AD = 6 cm, DB = 9 cm, AE = 8 cm, find the value of AC.

In a circle, PQ is diameter, RS is chord of length equal to radius of circle. PR and QS when produced intersect at point T. Find the ∠PTQ?

 If find the value of .