/sci/ - Science & Math

[Anonymous No.4130787]

does /sci/ want to help me with my homework?

Deres some proofs:

(1+tan^2x)(1+cos2x)=2

sin4A=4sinAcos^3A-4sin^3AcosA

[Anonymous No.4130805]

bump with more dog pictures

[Anonymous No.4130881]

[Anonymous No.4130907]

anyone wanna help a bruthu out?

[Anonymous No.4130910]

>>4130907
no cause you could google trigonometrics proofs and find these in 6 seconds

[Anonymous No.4130917]

>>4130910

jerk

[Anonymous No.4131006]

(1+tan^2(x))(1+cos(2x))
[1+(sin^2(x)/cos^2(x)][1+(2cos^2(x)-1)]
[(cos^2(x)/cos^2(x))+(sin^2(x)/cos^2(x))][1+(2cos^2(x)-1)]

4sin(A)cos^3(A)-4sin^3(A)cos(A)
[4sin(A)cos(A)][cos^2(A)-sin^2(A)]
[4sin(A)cos(A)][cos(2A)]

those should get you started. first one just requires simple algebra to complete. second one needs a substitution using a trig identity, and then a bit of recognition. ask if you need more, but at least try to make me believe you're making an effort.

[Anonymous No.4131027]

How2 all trig things ever (srsly):

1) Write everything in sines and cosines
2) Sub in (e^ix+e^-ix)/2 for cos x and (e^ix-e^-ix)/2i for sin x
3) If everything cancels, it's a valid identity. If not, it isn't.