find exact value of cos[tan-1(-1)+cos-1(-3/5)]
tan-1 is inverse tan
cos-1 is inverse cos
Hi
You've already been told how to start : expand $\displaystyle \cos\left[\arctan(-1)+\arccos\left(-\frac35\right)\right]$ using $\displaystyle \cos(a+b)=\cos a \cos b-\sin a \sin b$ with $\displaystyle a=\arctan(-1)$ and $\displaystyle b=\arccos\left(-\frac35\right)$.
By the way, $\displaystyle \arctan (-1)=-\arctan 1$ and you should know the value of $\displaystyle \arctan 1$.
You have posted seven (7) problems in four (4) posts. You have not shown ANY work at all. You have provided NO feedback to indicate whether you are learning anything. So far, you have managed to get others to do your homework for you. This will NOT serve you well on an examination. What's it going to be? Learning or just laziness? I can be harsh if you would like. So far, I'm just trying to get your attention. You WILL fail your class if you keep on this way. Pick a different path. Sooner is better.