Wie vereinfacht man f (theta) = sin4theta-cos6theta zu trigonometrischen Funktionen einer Einheitstheta?

Wie vereinfacht man f (theta) = sin4theta-cos6theta zu trigonometrischen Funktionen einer Einheitstheta?
Anonim

Antworten:

#sin (Theta) ^ 6-15cos (Theta) ^ 2sin (Theta) ^ 4-4cos (Theta) sin (Theta) ^ 3 + 15cos (Theta) ^ 4sin (Theta) ^ 2 + 4cos (Theta) ^ 3sin (Theta) -cos (Theta) ^ 6 #

Erläuterung:

Wir werden die folgenden zwei Identitäten verwenden:

#sin (A + -B) = sinAcosB + -cosAsinB #

#cos (A + -B) = cosAcosB sinAsinB #

#sin (4theta) = 2sin (2theta) cos (2theta) = 2 (2sin (theta) cos (theta)) (cos ^ 2 (theta) -sin ^ 2 (theta)) = 4sin (theta) cos ^ 3 (theta) -4sin ^ 3 (theta) cos (theta) #

#cos (6theta) = cos ^ 2 (3theta) -sin ^ 2 (3theta) #

# = (cos (2 theta) cos (theta) -sin (2 theta) sin (theta)) ^ 2- (sin (2 theta) cos (theta) + cos (2 theta) sin (theta)) ^ 2 #

# = (cos (theta) (cos ^ 2 (theta) - sin ^ 2 (theta)) - 2sin ^ 2 (theta) cos (theta)) ^ 2- (2cos ^ 2 (theta) sin (theta) + sin (Theta) (cos ^ 2 (Theta) -sin ^ 2 (Theta)) ^ 2 #

# = (cos ^ 3 (theta) -sin ^ 2 (theta) cos (theta) -2sin ^ 2 (theta) cos (theta)) ^ 2- (2cos ^ 2 (theta) sin (theta) + cos ^ 2 (Theta) sin (Theta) -sin ^ 3 (Theta)) ^ 2 #

# = (cos ^ 3 (theta) -3sin ^ 2 (theta) cos (theta)) ^ 2- (3cos ^ 2 (theta) sin (theta) -sin ^ 3 (theta)) ^ 2 #

# = cos ^ 6 (theta) -6sin ^ 2 (theta) cos ^ 4 (theta) + 9sin ^ 4 (theta) cos ^ 2 (theta) -9sin ^ 2 (theta) cos ^ 4 (theta) + 6sin ^ 4 (Theta) cos ^ 2 (Theta) -sin ^ 6 (Theta) #

# sin (4theta) -cos (6 theta) = 4 sin (theta) cos ^ 3 (theta) -4sin 3 (theta) cos (theta) - (cos ^ 6 (theta) -6sin ^ 2 theta) cos ^ 4 (theta) + 9sin ^ 4 (theta) cos ^ 2 (theta) -9sin ^ 2 (theta) cos ^ 4 (theta) + 6sin ^ 4 (theta) cos ^ 2 (theta) -sin ^ 6 (theta)) #

# = 4sin (theta) cos ^ 3 (theta) -4sin ^ 3 (theta) cos (Theta) -cos ^ 6 (theta) + 6sin ^ 2 (theta) cos ^ 4 (theta) -9sin ^ 4 (theta) cos ^ 2 (theta) + 9sin ^ 2 (theta) cos ^ 4 (theta) -6sin ^ 4 (theta) cos ^ 2 (theta) + sin ^ 6 (theta) #

# = sin (theta) ^ 6-15cos (theta) ^ 2sin (theta) ^ 4-4cos (theta) sin (Theta) ^ 3 + 15cos (Theta) ^ 4sin (Theta) ^ 2 + 4cos (Theta) ^ 3sin (Theta) -cos (Theta) ^ 6 #