CDS | Elementary Mathematics | 2 D Mensuration

ABCD passes through the centres of the three circles as shown in the figure where AB= 2 cm and CD= 1 cm. If the area of middle circle is the average of the areas of the other two circles, then what is the length (in cm) of BC?

Suppose P, Q and R are the mid-points of sides of a triangle of area 128 cm². If a triangle ABC is drawn by joining the mid-points of sides of triangle PQR, then what is the area of triangle ABC?

If the altitude of an equilateral triangle are increased by 20% while its area remains same, its corresponding base will have to be decreased by :

In a circle of radius 10.5 cm, the minor arc is one-fifth of the major arc. Find the area if the sector corresponding to the major arc.

A circular disc of radius 6 cm is divided into three sectors with central angles . Calculate the ratio of the areas of three sectors.