" Q."18" If "k=tan25^(@)" then "(k-1)/(k+1)+(k+1)/(k-1)=

If A+B+C=pi&sin(A+(C)/(2))=k(sin C)/(2), then (tan A)/(2)(tan B)/(2)= a.(k-1)/(k+1) b.(k+1)/(k-1) c.(k)/(k+1) d.(k+1)/(k)

sum_(k =1)^(n) k(1 + 1/n)^(k -1) =

If (k+(1)/(k))^(2)=16 , then k^(2)+(1)/(k^(2))=

If (sin x)/(a)=(cos x)/(b_(k))=(tan x)/(c)=k, then bc+(1)/(ck)+(ak)/(1+bk) is equal to k(a+(1)/(a)) (b) 1/k(a+(1)/(a))(1)/(k^(2))(d)(a)/(k)

Find sum_(k=1)^(n)(1)/(k(k+1)) .

A+ B = C and tan A = k tan B , then prove that sin (A-B) = (k-1)/(k+1) sin C

If t a ntheta_1t a ntheta_2=k , then ("cos"(theta_1-theta_2))/("cos"(theta_1+theta_2))= a. (1+k)/(1-k) b. (1-k)/(1+k) c. (k+1)/(k-1) d. (k-1)/(k+1)

If s e ctheta+t a ntheta=k ,\ costheta= a. (k^2+1)/(2k) b. (2k)/(k^2+1) c. k/(k^2+1) d. k/(k^2-1)