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Need Help with Maths - Trig

achu2k11

I am stuck on this question
1-(sinθ tanθ )/(1+secθ )≡cosθ

Help would be much appreciated :smile:

(edited 10 years ago)

Reply 1

joostan

Original post by achu2k11

I am stuck on this question
1-(sinθ tanθ )/(1+secθ )≡cosθ

Help would be much appreciated :smile:

What have you tried?

Spoiler

(edited 10 years ago)

Reply 2

joostan

Original post by TenOfThem

I assume that you are trying to prove the identity

Multiply out the brackets and see what happens

Isn't it a fraction? :s-smilie:

Reply 3

TenOfThem

Original post by joostan

Isn't it a fraction? :s-smilie:

oh yeah

missed the /

eyesight is not what it used to be

Reply 4

TenOfThem

Original post by achu2k11

I am stuck on this question
1-(sinθ tanθ )/(1+secθ )≡cosθ

Help would be much appreciated :smile:

Write all the parts using Sine and Cosine

Do you know how to get rid of a fraction in a fraction

Reply 5

achu2k11

i am still need help on it

Reply 6

joostan

Original post by achu2k11

i am still need help on it

So:

\ 1 -\dfrac{\sin(\theta)\tan(\theta)}{1+\sec(\theta)} \equiv \cos(\theta)[br]\Rightarrow 1 -\dfrac{\sin(\theta)\frac{\sin(\theta)}{\cos(\theta)}}{1+\frac{1}{\cos(\theta)}} \equiv \cos(\theta)

Spoiler

(edited 10 years ago)

Reply 7

davros

Original post by achu2k11

i am still need help on it

Start by multiplying numerator and denominator of your fraction by

cos \theta

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