Question

Решите плиззззз cos a- cos 2a-1/ sin a-sin 2a

Answer 1

$frac{cosa-cos2a-1}{sina-sin2a} = frac{cosa-(cos^2a-sin^2a)-1}{sina-2sina*cosa} = frac{cosa-cos^2a+sin^2a-1}{sina(1-2cosa)} =\= frac{cosa-cos^2a-(1-sin^2a)}{sina(1-2cosa)} = frac{cosa-2cos^2a}{sina(1-2cosa)} = frac{cosa(1-2cosa)}{sina(1-2cosa)} = frac{cosa}{sina} =ctga$