finding exact values

[nanase]

guys I need help with this,
I worked out the value of sin and cos already from a triangle diagram
but when I substituted i ended up with long expression that is not equal to the right figures.
Can somebody help me?

 

[Harry_the_cat]

What value/s did you get for sin and cos?

 

[Dr.Peterson]

View attachment 33557

guys I need help with this,
I worked out the value of sin and cos already from a triangle diagram
but when I substituted i ended up with long expression that is not equal to the right figures.
Can somebody help me?

The long expression I get can be simplified to that answer by rationalizing the denominator (among other things).

If you're saying that you tried evaluating your expression and it was different from the decimal value of what's shown, then either there's a mistake in your work so far, or you made a mistake in your evaluation. We can't tell where the error is without seeing it.

Show us your work so far, and we can check if it's right, and tell you what to do next.

 

[nanase]

sure thing, here we go

I feel my answer is going far away from the desired answer...
thanks for helping

 

[nanase]

The long expression I get can be simplified to that answer by rationalizing the denominator (among other things).

If you're saying that you tried evaluating your expression and it was different from the decimal value of what's shown, then either there's a mistake in your work so far, or you made a mistake in your evaluation. We can't tell where the error is without seeing it.

Show us your work so far, and we can check if it's right, and tell you what to do next.

most likely the "among other things" part that I miss hahaha

 

[BigBeachBanana]

Rationalize [imath]\frac{12}{\sqrt{13}}[/imath] and put the terms inside the parenthesis over one fraction. Should be obvious from there.

 

[Harry_the_cat]

After you sub in values for sin and cos, I'd multiply by \(\displaystyle \frac{\sqrt{13}}{\sqrt{13}}\) to get rid of fractions over fractions.

 

[nanase]

Gee thanks BigBeachBanana & Harry_the_cat !! I tried both of your approaches and it works!
Appreciate the help!