+118616 ctga-sin2a=ctga x cos2a prove dath :/
\(cot(a)-sin(2a)=cot(a) \times cos(2a)\\ RHS=cot(a)-sin(2a)\\ RHS=cot(a)-2sin(a)cos(a)\\ RHS=cot(a)-\frac{2sin(a)cos(a)cot(a)}{cot(a)}\\ RHS=cot(a)\left(1-\frac{2sin(a)cos(a)}{cot(a)}\right)\\ RHS=cot(a)\left(1-\frac{2sin(a)cos(a)sin(a)}{cos(a)}\right)\\ RHS=cot(a)(1-2sin^2(a))\\ RHS=cot(a)(cos(2a))\\ RHS=LHS\\ \)
Next time a please would be appreciated :/
