Use the addition and subtraction formulas to find the exact value of the expression.
Tan 165 degrees.

Question

Use the addition and subtraction formulas to find the exact value of the expression.
Tan 165 degrees.

zepdrix · Answer

Hmmm I think they probably want you to break it up like this.
$$\large \tan(165^o)=\tan(135^o+30^o)$$

anonymous · Answer

what would you do next?

zepdrix · Answer

$$\large \tan (a+b)=\frac{ \tan a + \tan b }{ 1- \tan a \tan b }$$
Hmmm we can use the sum formula for tangent.
135 and 30 both correspond to special angles for the tangent, so it will break down pretty nicely.

zepdrix · Answer

$$\large \tan(135+30)=\frac{ \tan135+\tan30 }{ 1-\tan135 * \tan30 }$$
Understand the setup? :D

anonymous · Answer

well i tried it like this and it doesnt work out, or idk what to do next

anonymous · Answer

sorry its backwards! :o

zepdrix · Answer

lolol backwards XD

anonymous · Answer

haah idk how to fix it :/

zepdrix · Answer

Oh i see, you broke up the numbers differently.
Looks like you were able to break it up so they're still special angles though, so that's good :) hmm

zepdrix · Answer

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