147 reputation
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location Switzerland
age 25
visits member for 1 year, 3 months
seen Feb 9 at 16:55

Feb
9
accepted Proving double-angle trig identities
Feb
9
comment Proving double-angle trig identities
Wait, I got it. Thanks!
Feb
9
comment Proving double-angle trig identities
@labbhattacharjee Thanks. One final question: how do you get from $\frac{\cos^2A+\sin^2A}{\cos^2A-\sin^2A}$ to $\frac1{\cos2A}$?
Feb
9
comment Proving double-angle trig identities
How did you get from $\frac{1+\tan^2A}{1-\tan^2A}$ to $\frac{\cos^2A+\sin^2A}{\cos^2A-\sin^2A}$?
Feb
9
asked Proving double-angle trig identities
Feb
8
comment Proving a trig identity
I see it now. Thanks guys
Feb
8
accepted Proving a trig identity
Feb
8
comment Proving a trig identity
How does $\frac{1 - tanAtanB}{1 + tanAtanB} = \frac{cosAcosB - sinAsinB}{cosAcosB + sinAsinB}$?
Feb
8
accepted Find parallel vector with vector equation of a straight line
Feb
8
asked Proving a trig identity
Jan
31
comment Find parallel vector with vector equation of a straight line
I think I know why: all I need to do is apply $λ$ to b rather than the whole r equation. By multiplying everything by 4 and dividing everything by √5 you get there...
Jan
31
asked Find parallel vector with vector equation of a straight line
Jan
24
awarded  Scholar
Jan
24
accepted Reducing quartic equations to quadratic
Jan
24
awarded  Student
Jan
24
asked Reducing quartic equations to quadratic
Feb
16
awarded  Autobiographer
Jan
15
awarded  Supporter