Question

вычислите............

Answer 1

$\frac{1 - sina - cos2a}{sin2a - cosa} = \frac{sin^2a + cos^2a-sina - cos^2 + sin^2a}{2sinacosa - cosa} = \frac{sina(2sina - 1)}{cosa(2sina - 1)} = \frac{sina}{cosa} = \frac1{ctga} = 3$