Wednesday

April 23, 2014

April 23, 2014

Posted by **Edward** on Wednesday, April 11, 2007 at 2:25pm.

3sinxtanx=8

I would do it this way:

sinxtanx = 8/3

sinx(sinx/cosx)=8/3

sin^2x/cosx = 8/3

(1-cos^2x)/cosx=8/3

cross-multiply

3 - 3cos^2x = 8cosx

3cos^2x + 8cosx - 3 = 0

(3cosx-1)(cosx+3)=0

cosx=1/3 or cosx = -3

the last one is not possible

so x = arccos(1/3)=70.5º

or 289.5º (in the fourth quadrant)

**Related Questions**

Trig........ - I need to prove that the following is true. Thanks (cosx / 1-sinx...

Trigonometry. - ( tanx/1-cotx )+ (cotx/1-tanx)= (1+secxcscx) Good one! ...

Trig - prove the identity (sinX)^6 +(cosX)^6= 1 - 3(sinX)^2 (cosX)^2 sinX^6= ...

maths - trigonometry - I've asked about this same question before, and someone ...

trig - express this in sinx (1/ cscx + cotx )+ (1/cscx- cotx) i got 2sinx is ...

Trigonometic - Solving Trigonometic Equations solve for x and give the answers ...

Trig....... - I need to prove that the following is true. Thanks (2tanx /1-tan^x...

Math 12 - Simplify #1: cscx(sin^2x+cos^2xtanx)/sinx+cosx = cscx((1)tanx)/sinx+...

Trigonometry - Simplify #1: cscx(sin^2x+cos^2xtanx)/sinx+cosx = cscx((1)tanx)/...

Mathematics - Trigonometric Identities - Prove: (tanx)(sinx) / (tanx) + (sinx...