Question

Give an example of a real number t for which cos t is positive and sin t is negative.

Answer 1

Question:Give an example of a real number t for which cos t is positive and sin t is negative.

Solution: As we know $f(x)=\cos x$ is an even function($f(-x)=f(x)$) and $g(x)=\sin x$ is an odd function($f(x)=f(-x)$). So to solve this problem we can use real number x from (-$\frac{\pi}{2}$,0). For example: -1.0

$\sin\left(-1.0\right)=-0.841470984$

$\cos\left(-1.0\right)=0.5403023058$

Answer: -1.0