Saturday

September 20, 2014

September 20, 2014

Posted by **lindsay** on Tuesday, May 1, 2012 at 4:35pm.

- trigonometry -
**Reiny**, Tuesday, May 1, 2012 at 4:52pmtan(A-B) = (tanA - tanB)/(1+tanAtanB)

but tanA = 2tanB

so above

= (2tanB - tanB)/(1 + 2tanBtanB)

= tanB/(1+2tan^2B)

= (sinB/cosB) / (1 + 2sin^2 B /cos^2 B)

= sinB/cosB /[(cos^2 B + 2sin^2 B)/cos^2 B]

= (sinB/cosB) * (cos^2 B)/(cos^2 B + 2sin^2 B)

= sinBcosB /(cos^2 B + 2(1 - cos^2 B) )

= sinBcosB / (2 - cos^2 B)

= 2sinBcosB/ (4 - 2cos^2 B)

= sin 2B / (4 - 2cos^2 B)

which is different from yours,

I can't seem to find my error if there is one.

**Answer this Question**

**Related Questions**

Trigonometry - Find the exact value of tan(a-b) sin a = 4/5, -3pi/2<a<-pi...

trig - evaluate the following in exact form, where the angeles alpha and beta ...

Calculus - The question will first read in English followed by a reading in ...

Trigonometry - Prove that tan (Beta) sin (Beta) + cos (Beta) = sec (Beta) Please...

physics - Two radar stations A and B, are separated by horizontal distance of (...

Math - Given that sin alpha=4/sqrt65, pi/2<alpha<pi, and cos beta=-3/...

Trig - Use the fundamental identities to simplify the expression: cot beta sec ...

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

trig - verify the identity: sec(beta)+ tan (beta)= cos(beta)/ 1-sin(beta)

maths --plse help me.. - The angle of elevation of the top of a tower as ...