The radii of two circles are 19 cm and 9 cm respectively. Find the radius of the circle which has circumference equal to the sum of the circumferences of the two circles.

In the given figure, $AB\parallel CD, \angle ABO=40°$ and $\angle CDO=35°$. Then the value of $x$ will be

Only one circle can be drawn through three non collinear points.

The wheels of a car are of diameter $80 \mathrm{c}\mathrm{m}$ each. How many complete revolutions does each wheel make in 10 minutes when the car is traveling at a speed of $66 \mathrm{k}\mathrm{m}$ per hour? $\left(\mathrm{use} \pi =\frac{22}{7}\right)$

Name the diameter of the circle.

Name the chord of the circle.