Posted by **Evelina** on Saturday, November 12, 2011 at 10:45am.

How to do this one?

(sina/1-cosa) + (1-cosa/sina) =

Also, wanted to ask if I did another one right:

1 - sin^2a + tg^2a * cos^2a = 1 - sin^2a + (sina/cosa)^2 * cos^2a = 1 - sin^2a + sin^2a = 1 ???

- trig -
**Steve**, Saturday, November 12, 2011 at 7:08pm
That's not what I get.

(1-cosa)/sina = tan(a/2)

so, you have

1/tan(a/2) + tan(a/2)

= (1 + tan^2(a/2))/tan(a/2)

= sec^2(a/2)/tan(a/2)

= 1/cos^2(a/2) * cos(a/2)/sin(a/2)

= 1/sin(a/2)cos(a/2) = 2/sina

- trig -
**Adi**, Wednesday, July 20, 2016 at 3:33am
Well it goes like this :

sinA/1-cosA + 1-cosA/sinA

= sin^2A + (1-cosA)^2/(1-cosA)sinA (cross multiplying)

= sin^2A + cos^2A + 1 - 2cosA/(1-cosA)sinA

= 1 + 1 - 2cosA/(1-cosA)sinA

(sin^2A + cos^2A =1)

= 2 - 2cosA/(1-cosA)sinA

= 2 (1-cosA)/(1-cosA)sinA

= 2/sinA

## Answer This Question

## Related Questions

- further mathematics - Let P=(cosA sinA) (sinA cosA) Q=(cosB sinA) (sinB cosA) ...
- Maths - Hi, can someone give me the answer to this question: secA-tanA=1/4. Find...
- math (trig) - i have some problems doing trig the first one is: Show that cos(x/...
- trigonometry - x×sin^3A=y , cos^3A = sinA × cosA , x×sinA= y×cosA , then prove ...
- Maths - Prove that [sinA/(1-cosA)-(1-cosA)/sinA]*[cosA/(1+sinA)+(1+sinA)/cosA]=...
- Trigonometry - I need to prove that the following is true. Thanks. csc^2(A/2)=...
- Trig - Please help with this one. I've worked it out in so many ways and can't ...
- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- trig - I need to count this: a) 1-tg^2a/1+ctg^2a, when sina =2/3 b) 1-tg^2a/1-...
- trig - Please help me how to do this: 1) 1 + sina*cosa / (cosa + sina)^2 = 2) ...

More Related Questions