Radius of circumcircle of `/_\DEF` is
`(A) R`
`(B)` `R/2`
`(C)` `R/4`
`(D)` none of these

Maximum value of a for which range of function y=log_(2)(x^(2)-4x+a) is R, is : (A) 4 (B) 2 (C) -4 (D) None of these

In A B C ,(a b-r_1r_2)/(r_3),w h e r ea ,b ,r_1r_2, r_3, Randr have usual meanings, is equal to (A) R (B) 2R (C) r (D) none of these

If a=sum_(r=1)^oo(1/r)^2, b=sum_(r=1)^oo1/((2r-1)^2), then a/b= (A) 5/4 (B) 4/5 (C) 3/4 (D) none of these

In an equilateral triangle, inradius r , circumradius R and ex-radius r_1 are in A.P. (b) G.P. (c) H.P. (d) none of these

If C_r stands for ^nC_r and sum_(r=1)^n (r.C_r)/(C_(r-1)=210 then n= (A) 19 (B) 20 (C) 21 (D) none of these

If the sum of the areas of two circles with radii r_1 and r_2 is equal to the area of a circle of radius r , then r_1^2 +r_2^2 (a) > r^2 (b) =r^2 (c)

The range of the function f(x)=(x^2-x)/(x^2+2x) is R (b) R-[1] (c) R={-1/2,1} (d) none of these

In an equilateral triangle,the inradius and the circumradius are connected by r=4Rb .r=R/2 c.r=R/3 d.none of these

For a matrix A of rank r (A) rank (A\')ltr (B) rank (A\')=r . (C) rank (A\')gtr (D) none of these

If R is the largest equivalence relation on a set A and S is any relation on A , then RsubS (b) SsubR (c) R=S (d) none of these