you have to solve it step by step going downwards ang pagsusulat para hindi nakakalito. do not go for shortcuts. You need to reinstate yung identities na ginamit mo kung bakit nagbago yung double angle papunta sa single angle. Huwag yung patalun-talun....pababa ang sulat step by step bagalan mo lang. Remember hindi lahat ng tao ganun kabilis pumick up sa Math. I watch videos ni PreMath...cya dahan dahan lang mag explain. Do that.
2 (sin^2)A + 2sinAcosA / 2 cos^2 A = 2(sin^2 A + sinAcosA) / 2 cos^2 A , then simplify the 2, become sin^2 A / cos^2 A + sinAcosA/cos^2 A = tan^2 A + tan A=6