A circle has points P, Q, R on a circle in such a way that angle PQR is 60 deg and angle QRP is 80 deg. Calculate the angle subtended by an arc QR at the centre.
If the amount received at the end of 2nd and 3rd year as Compound Interest on a certain Principal is Rs 2100, and Rs 2268 respectively, what is the rate (in %) of interest?
ΔABC is a right angled triangle, the radius of its circumcircle is 3 cm and the length of its altitude drawn from the opposite vertex to the hypotenuse is 2 cm. Then the area of the triangle is