# Find tan from sin.

• February 26th 2011, 10:06 AM
arm
Find tan from sin.
Let $sin \alpha =\frac{-1}{4}, \pi < \alpha < \frac{3\pi }{2}$.
Find: $tan(\alpha -\frac{25\pi }{4})$
• February 26th 2011, 10:24 AM
skeeter
Quote:

Originally Posted by arm
Let $sin \alpha =\frac{-1}{4}, \pi < \alpha < \frac{3\pi }{2}$.
Find: $tan(\alpha -\frac{25\pi }{4})$

draw a reference triangle in quad III, use the given $\sin{\alpha} = -\dfrac{1}{4}$ to determine the value of $\cos{\alpha}$ , then use the ratio identity to find $\tan{\alpha}$ , finally use the difference identity for tangent to finish.

btw ... you need to be sharing what you've attempted on all those other posts.