mathnoob1
show cos2x = 1 - tan^2 (x) /
1 +tan^2 (x)
Delete
Share
This Question is Closed
Nikhil619
Best Response
You've already chosen the best response.
1
do u know how to start?
mathnoob1
Best Response
You've already chosen the best response.
0
|dw:1359466433151:dw|
mathnoob1
Best Response
You've already chosen the best response.
0
|dw:1359466643501:dw|
Nikhil619
Best Response
You've already chosen the best response.
1
Umm...dont do that...u'll only get cos2x=1...
Nikhil619
Best Response
You've already chosen the best response.
1
what is tanx=?i.e what can tanx be written as?
mathnoob1
Best Response
You've already chosen the best response.
0
sinx/cosx?
Nikhil619
Best Response
You've already chosen the best response.
1
yeah good..so tan^2x = sin^2 x/cos^2 x ?
mathnoob1
Best Response
You've already chosen the best response.
0
ya
Nikhil619
Best Response
You've already chosen the best response.
1
so nw substitute...and tell me what u get..
mathnoob1
Best Response
You've already chosen the best response.
0
1-(sin(^2)x/cos(^2)x /
1+(sin(^2)x/cos(^2)x ?
Nikhil619
Best Response
You've already chosen the best response.
1
take lcm..
Nikhil619
Best Response
You've already chosen the best response.
1
Simplify more...
Tushara
Best Response
You've already chosen the best response.
1
i hope dis helps
Nikhil619
Best Response
You've already chosen the best response.
1
@mathnoob1 u got it?
mathnoob1
Best Response
You've already chosen the best response.
0
do we use tan^2+1=sec^2
and 1+cot^2 =csc^2 for proving?
Nikhil619
Best Response
You've already chosen the best response.
1
U can use any Identity for proving but here as far as I know only this will work...
mathnoob1
Best Response
You've already chosen the best response.
0
any tips to know which identity fit most?
Nikhil619
Best Response
You've already chosen the best response.
1
there aren't any methods or anything..see u have 2 sides of a proof right..one side will be some complicated thing...while the other will probably be sumthin u know the direct equation for like here cos2x=cosx-sinx...this u already know...so try converting the complicated thing in terms of the other side equation....
mathnoob1
Best Response
You've already chosen the best response.
0
ok
mathnoob1
Best Response
You've already chosen the best response.
0
i got it cos2x/1 = cos2x