If radius of a sphere is decreased by 48%, then by what percent does its surface area decrease?

What can be the maximum number of common tangent, which can be drawn to two non-intersecting circles? 

Triangle PQR is inscribed in a circle such that P, Q and R lies on the circumference . If PQ is the diameter of the circle and ∠PQR = 40 ° , then what is the value ( in degrees ) of ∠QPR ?

In ΔPQR, PQ=QR and O is an interior point of ΔPQR such that ∠OPR=∠ORP.

Consider the following statements:

(i) ΔPOR is an isosceles triangle.

(ii) O is the centroid of ΔPQR.

(iii) ΔPQO is congruent to ΔRQO.

Which of the above statements are correct?

If the ratio of the heights of two identical triangles is 4: 9, find the ratio of the areas of the two triangles.

The area of a rhombus is 144 square units. The length of one of its diagonals is twice the length of other diagonal. What is the sum of length of its diagonals?

Triangle PQR is such that PQ=9 cm, QR=6 cm, PR=7.5 cm and triangle PQR is similar to triangle XYZ. If XY=18 cm, find the value of YZ.

If one of the equal angles of an isosceles triangle is 65°, then the angle at the vertex is