Cambridge Trig Identities (1 Viewer)

[kazemagic]

Need help with 11,h and 13,c please, and I don't know how to start question 14,a)
Any help would be greatly appreciated. Thanks!

 

[RivalryofTroll]

Need help with 11,h and 13,c please.
Thanks!

11. h. LHS = 1-tan^2x + sec^2x
= 1 - tan^2x + (1+tan^2x) [since sec^2x - tan^2x = 1]
= 2
= RHS

 

[AAEldar]

11h)













13c)

 

[kazemagic]

Ahhh thanks Troll and Aldar!
Now I just need help to start question 14a lol

 

[zeebobDD]

FOr 14_ remember that cos^0 +sin^0=1 therefore squaring both side, thats how you start it

 

[kazemagic]

Ahhh I see. Thanks Zeeb!

 

[kazemagic]

Got another question.

Cambridge sure knows how to piss me off =.=

 

[AAEldar]

 

[RivalryofTroll]

Got another question.

Cambridge sure knows how to piss me off =.=

LHS
= secx - tanx
= 1/cosx - sinx/cosx
= 1-sinx/cosx
= 1-sinx/cos mutiply (1+sinx)/(1+sinx)
= 1-sin^2x/cosx(1+sinx)
= cos^2x/cosx(1+sinx) (since sin^2x + cos^2x = 1, then cos^2x = 1 - sin^2x)
= cosx/1+sinx
= RHS

 

[kazemagic]

Thanks Eldar, I know how to get from the first equation to the last one(I don't know why you needed to times cos theta/cos theta though) The problem is the middle equation O_O What the hell is it doing there?!

EDIT: Nvm thanks Troll. Got it!

 

[RivalryofTroll]

Thanks Eldar, I know how to get from the first equation to the last one(I don't know why you needed to times cos theta/cos theta though) The problem is the middle equation O_O What the hell is it doing there?!

Look at the post above by me son!

 

[AAEldar]

Thanks Eldar, I know how to get from the first equation to the last one(I don't know why you needed to times cos theta/cos theta though) The problem is the middle equation O_O What the hell is it doing there?!

EDIT: Nvm thanks Troll. Got it!

Well RivalryofTroll just showed how to do it (as you saw).

The reason I multiplied by cos/cos was because that is essentially 1, so I'm not really doing anything to the equation but just making it look different - which happened to be the quick way to get it to the other side.

 

[kazemagic]

O_O sorry I don't see any reason why you need to times cos theta/ cos theta to get to that last equation. If you are talking about the 2nd equation to the last equation, then I must be too inexperienced to understand it. Thanks anyways