Saturday

September 20, 2014

September 20, 2014

Posted by **Sarah** on Sunday, January 27, 2013 at 1:28pm.

tan(x/2) =( plus/minus) sqrt(1-cos(x/1+cos(x))

- Trig -
**Reiny**, Sunday, January 27, 2013 at 4:00pmnot true, if you meant:

tan(x/2) =( plus/minus) sqrt(1-cos(x/(1+cos(x)))

let x = 2 radians

LS = tan 1 = appr 1.557

RS = ± √(1 - cos( 2/(1 + cos 2)

let's look at cos (2/(1+ cos2)

= cos(2/.58385)

= cos(3.4255) = -.95996

so RS = ± √( 1 - (-.95996) = ±√1.95996 = ± 1.4

≠ LS

If done the way you typed it

LS = tan 1 = appr 1.557

RS = ±√(1 - cos(2/1 + cos2)

= ± √( 1 - cos(1.5868..)) = ± 1.0065 ≠ LS

so check your equation, or your typing

**Answer this Question**

**Related Questions**

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

Trigonometry desperate help, clueless girl here - 2. solve cos 2x-3sin x cos 2x...

calculus - Differentiate. y= (cos x)^x u= cos x du= -sin x dx ln y = ln(cos x)^x...

Calc. - Differentiate. y= (cos x)^x u= cos x du= -sin x dx ln y = ln(cos x)^x ln...

Trigonometry - 1.Solve tan^2x + tan x – 1 = 0 for the principal value(s) to two ...

precalculus - For each of the following determine whether or not it is an ...

Trig. - sec^2xcotx-cotx=tanx (1/cos)^2 times (1/tan)-(1/tan)=tan (1/cos^2) times...

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

trigonometry hlp me - 6.Prove that tan y cos^2 y + sin^2y/sin y = cos y + sin y...

trig help much appreciated! :)) - 1. Find the complete exact solution of sin x...