## anonymous one year ago what are the steps I need to take to answer these questions Find the exact value of each expression. Do not use calculator cos(sin^-1(3/5)) and Find exact value of the expression sin(cos^-1 (5/13)-cos^-1 (4/5))

1. freckles

you could let u=arcsin(3/5) so sin(u)=3/5 and you are trying to find cos(u) given sin(u)=3/5 |dw:1436832595334:dw|

2. freckles

that one thing is suppose to be u

3. freckles

the second one I would expand and make two right triangles

4. freckles

expand using: $\sin(a-b)=\sin(a)\cos(b)-\sin(b)\cos(a)$

5. anonymous

so would cos u =4/5 for the first one?

6. freckles

yes

7. anonymous

cool :) can you show me how to set up the second one I'm a little confused on how it would look like

8. freckles

my thing isn't notifying me when people reply $\sin(a-b)=\sin(a)\cos(b)-\sin(b)\cos(a) \\ \text{ where } a=\arccos(\frac{5}{13}) \text{ and } b=\arccos(\frac{4}{5} ) \\ \text{ so } \cos(a)=\frac{5}{13} \text{ and } \cos(b)=\frac{4}{5}$ find sin(a) and cos(b) in a similar way you did for the previous question

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