Question

- sinβ • tgβ - cosβ

Answer 1

-sinβ • tgβ - cosβ =
= -sinβ • $\frac{sin \beta }{cos \beta }$ - cosβ =
= $\frac{-sin^2 \beta }{cos \beta }$ - cosβ =
= $\frac{-sin^2 \beta - cos^2 \beta }{cos \beta }$ =
= $-\frac{sin^2 \beta + cos^2 \beta }{cos \beta }$ =
= $-\frac{1}{cos \beta }$