Trigonometric identities Quiz

1. $\cos\theta=\frac35$ and $\theta$ is acute. Find $\tan\theta$.

• A. $\frac34$
• B. $\frac54$
• C. $\frac45$
• D. $\frac43$

2. Simplify $1-\cos^2x$.

• A. $\sin^2x$
• B. $\sin x$
• C. $-\sin^2x$
• D. $\tan^2x$

3. Simplify $\dfrac{\sin^2x}{\tan x}$.

• A. $\cos x$
• B. $\tan x$
• C. $\sin x\cos x$
• D. $\sin^2x$

4. $\sin\theta=-\frac45$ and $\theta$ is in the third quadrant. Find $\cos\theta$.

• A. $\frac35$
• B. $-\frac35$
• C. $\frac{9}{25}$
• D. $-\frac{9}{25}$

5. Which expression is identical to $\dfrac{\sin^2x}{1-\sin^2x}$?

• A. $\cos^2x$
• B. $\frac{1}{\tan^2x}$
• C. $\sin^2x$
• D. $\tan^2x$