Question

Hey guys can I get some help?! I need step by step instruction when evaluating sin(Cos^-1(4/5)+Tan^1(3/4)). What is an identity used in the solution?

a. sin ( x + y) = sin x cos y - cos x sin y
b. sin ( x + y) = cos x cos y + sin x sin y
c. sin ( x + y) = sin x cos y + cos x sin y
d. sin ( x + y) = cos x cos y - sin x sin y

Answer 1

\(\cos^{-1}(\frac{4}{5}) + \tan^{-1}(\frac{3}{4})\)

Is that right?

Answer 2

Yes, that's right

Answer 3

@Hero

Answer 4

I'm stumped.

Answer 5

sin(Cos^-1(4/5)+Tan^1(3/4)) I think you forgot the sin in front

Answer 6

:(

Answer 7

Identity that will be used in this solution will be the first one i.e. A

Answer 8

sorry my Bad you have to go for third Identity i.e. C

Answer 9

Oh, can you please show me how you got that??

Answer 10

you know that formula for Identity Sin(A+B)
= CosA*SinB+SinA*CosB

Answer 11

Can i give an idea here if you guys don't mind

Answer 12

then we have to use the same formula
@godorovg go ahead

Answer 13

Oh O.K. Yes please do @godorovg

Answer 14

we know sin/cos = tan is right/ so why want sub in and slove in this manner

Answer 15

and work backwards just a thought

Answer 16

like this tan a-b/ cos a-b =sin a-b /2/sin a-b2 =sin a-b /ctn C/2 and so on

Answer 17

thoughts here

Answer 18

Oh ok. And that gives us c. as well?

Answer 19

@godorovg

Answer 20

yes it should if done right

Answer 21

Thank you for your input!

Answer 22

does that make sense to you??