In Radius

Q. If r is the radius and R is the circumradius. Then $2R\le r$

1. True
2. False

Q. The incircle of $△ABC$ having integral side lengths and least perimeter, touches $AB,BC,CA$ at $R,P,Q$ respectively. If $\frac{2}{AR}+\frac{5}{BP}+\frac{5}{CQ}=\frac{6}{r}$, where $r$ is the radius of the incircle, then

1. $\Delta ABC\text{is isosceles}$
2. $\Delta ABC\text{is equilateral}$
3. $\text{Area of}△ABC\text{is 27 sq. units}$
4. $\text{Inradius of}△ABC\text{is 4 units}$

Q. 33 If A and B be two sets such that n(A)=15, n(B)=25, then number of possible value of n(AΔ B)

Q. differentiate x + 1/x from first principle