If `A+B+C=pi//2` , show that `cotA+cotB+cotC=cotAcotBcotC`

Prove that cotA-tanA=2cotA

If A+B+C=pi . Then prove that cosA=-cos(B+C)

If A+B=pi/4 show that (1+tanA)(1+tanB)=2

If tanA+tanB=a and cotA+cotB=b prove that cotA cotB= b/a

If A+ B + C = pi, then cos^(2) A + cos ^(2) B + cos ^(2) C is equal to : A) 1 - cos A cos B cos C B) 1 - 2 cos A cos B cos C C) 2 cos A cos B cos C D) 1 + cos A cos B cos C

If tan(A+B)=(tanA+tanB)/(1-tanAtanB) , then by applying the result tantheta=(1/cottheta) prove that cot(A+B)=(cotAcotB-1)/(cotA+cotB)

If a cos theta+b sin theta=c , show that asin theta-bcos theta=pm sqrt((a)^(2)+(b)^(2)-(c)^(2))

If A+B+C =pi prove that sin2A=-sin(2B+2C)

If a, b, c are positive and unequal show that value of the determinant Delta=|[a, b, c],[ b, c, a],[ c, a, b]| is negative.

Show that A cap B = A cap C need not imply B = C