abc12313 2 years ago Find the exact value of sin (arccos (3/5)). For full credit, explain your reasoning.

1. myininaya

So if we have x=arccos(3/5) then cos(x)=3/5. Draw a right triangle and use cos(x)=3/5 to find the other missing leg. then evaluate sin(x)

2. calmat01

Myininaya has it down, abc. You should follow myininaya's hint.

3. abc12313

im sorry i still dont understand it could you explain it more? like is it like pythagorean therom?

4. calmat01

Exactly. recall that cosx is just adjacent over the hypotenuse. So, your adj side is 3 and your hypotenuse is 5. Now just find the missing side by applying pythagorean's theorem and then go back and answer your question.

5. abc12313

would it be 4/5?

6. phi

yes For full credit, explain your reasoning.

7. abc12313

I drew a right triangle I used cos(x)=3/5 to find the other missing leg. I know that cosx is just adjacent over the hypotenuse. So, the adj side is 3 and your hypotenuse is 5. I found the missing side by applying pythagorean's theorem and my answer is 4/5

8. abc12313

@phi is this a good answer?

9. phi

yes, sounds good (but I would leave out the "just" in "just adjacent over hypotenuse" I found the missing side by applying pythagorean's theorem I would add "and it is 4" then add the definition of the sin: opposite over adjacent

10. abc12313

okay thank you so much everyone for all of your help!!!