Friday

January 30, 2015

January 30, 2015

Posted by **Riley** on Sunday, November 14, 2010 at 10:00pm.

- Pre-Calculus -
**Reiny**, Sunday, November 14, 2010 at 10:30pmYou should recognize the 8,15,17 and 5,12,13 right-angled triangles

so in II if

sinØ= 15/17, then cosØ = -8/17 and tanØ = - 15/8

cosß = -5/13 , then sinß = 12/13 and tanß = -12/5

tan(Ø+ß) = (tanØ + tanß)/(1 - tanØtanß)

= ....

you finish the arithmetic.

- Pre-Calculus -
**Riley**, Sunday, November 14, 2010 at 10:41pmOk i understand until you say that tan(theta) +tan(beta) needs to be divided by 1-tan(theta)tan(beta) where does that come from?

- Pre-Calculus -
**Reiny**, Sunday, November 14, 2010 at 10:54pmI assumed you knew the formulas, since you have know them to do these kind of problems

look under "other identities"

http://library.thinkquest.org/20991/alg2/trigi.html

- Pre-Calculus -
**Daniel**, Sunday, November 14, 2010 at 11:00pmI do but why did u use that one. Im trying to understand because i have a test tomorrow and i have to do well on it.

- Pre-Calculus -
**Reiny**, Sunday, November 14, 2010 at 11:18pmwell, it asked for tan(Ø+ß) didn't it?

The letters themselves of course don't matter

e.g.

tan(A+B) =(tanA + tanB)/(1- tanAtanB)

**Answer this Question**

**Related Questions**

Pre Calc. - Use the sum or difference identity to find the exact value of sin255...

Algebra 2/ trig - sin theta= 7/25, 0< theta < pi/2 cos beta=8/17, 0, beta...

Math - Does 'using the unit circle' just mean that I use these: In Quadrant I, ...

Calculus - I wanted to confirm that I solved these problems correctly (we had to...

pre calc - suppose beta is an angle in the second quadrant and tan beta=-2. ...

math - How would you establish this identity: (1+sec(beta))/(sec(beta))=(sin^2(...

trig - If sin theta is equal to 5/13 and theta is an angle in quadrant II find ...

easy trig - If sin(theta)=[sqrt(70)]/7 and theta is in Quadrant two, find the ...

simple trig - If sin(theta)=[sqrt(70)]/7 and theta is in Quadrant two, find the ...

math (trig) - if cos 2 theta = -(1/3) and theta is in Quadrant 2, find sin theta...