## anonymous 4 years ago Mk, I'm really not sure about this one. If it helps here is the multiple choice: If sinhx=8/15, find the values of the other hyperbolic functions at x.

1. anonymous

2. asnaseer

Use the relation:$\cosh^2(x)-\sinh^2(x)=1$

3. asnaseer

there are other relations you can use as well, e.g.:$\tanh^2(x)=1-sech^2(x)$$\coth^2(x)=1+csch^2(x)$

4. anonymous

Well from elimination, it can only be 2 or 4 since sinhx=8/15, So cosh^2x = 8/15 + 1, correct?

5. anonymous

correct?

6. asnaseer

not quite:$\cosh^2(x)=1+\sinh^2(x)=1+\frac{64}{225}=\frac{289}{225}$therefore:$\cosh(x)=\sqrt{\frac{289}{225}}=\frac{17}{15}$