Sunday

December 21, 2014

December 21, 2014

Posted by **lindsay** on Saturday, April 21, 2012 at 5:46pm.

a. 8 cos x sin x = sin x

b. 5 tan^2 y + 5 tan y = 2 sec^2 y.

- trigonometry -
**Reiny**, Saturday, April 21, 2012 at 6:09pma)

8cosxsinx - sinx = 0

sinx(8cosx - 1) = 0

sinx = 0 or cosx = 1/8

if sinx = 0 , x = 0, 180, 360

if cosx = 1/8, x = 82.8° or 277.18°

working on the 2nd....

- trigonometry -
**Reiny**, Saturday, April 21, 2012 at 9:13pmb)

5 tan^2 y + 5 tan y = 2 sec^2 y

playing around with some right-angled triangles, using the numbers 2 and 5

I drew a triangle with base 1, height 2 and hypotenuse 5

let the base angle be y

then tany = 2/1 , y = 63.4349...° ( stored in memory)

checking:

LS = 5(2/1)^2 + 5(2/1) = 30

RS = 2/(1/√5)^2 = 10

ahh, but if tany = -2/1

LS = 5(-2/1)^2 + 5(-2/1) = 10

RS = 1/(1/√5)^2 = 10

so we need y = 180-63.4349 or y = 360-63.4349

y = 116.565° or y = 296.565°

**Answer this Question**

**Related Questions**

Trigonometry - I have some trigonometric equations to do, but I'm pretty lost, ...

Trigonometry - Please review and tell me if i did something wrong. Find the ...

trigonometry (please double check this) - Solve the following trig equations. ...

Trigonometry - Solve the following trig equations. Give all positive values of ...

MathsSs triG - Consider sin(x-360)sin(90-x)tan(-x)/cos(90+x) 1.A.SIMPLIFY sin(x-...

tigonometry - expres the following as sums and differences of sines or cosines ...

trigonometry (please double check this) - Solve the following trig equations. ...

Trig - Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 < v < ...

Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...

Algebra II - Multiple Choice (theta) means the symbol 0 with the dash in it. 1.)...