If diagonals of a rhombus are 16 cm and 30 cm. then what is the perimeter (in cm) of the rhombus?

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

Given that (a²+b²)=60, then find the value of (a+b)²+(a–b)².

If AD, BE and CF are medians of ∆ABC, then which one of the following statements is correct? 

AD is the median of a triangle ABC and O is the centroid such that AO = 10 cm. The length of OD (in cm) is 

A solid sphere of diameter 7 cm is cut into two equal halves. What will be the increase (in cm.²) in the total surface area?

A field in the shape of a trapezium whose parallel sides are 200 meter and 400-meter-long, whereas each of other two sides is 260 meter long. What is the area (in m²) of the field?

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