Cevap:
Açıklama:
İspat: - günah (7 teta) + günah (5 teta) / günah (7 teta) -sin (5 teta) =?
(sin7x + sin5x) / (sin7x-sin5x) = tan6x * cotx rarr (sin7x + sin5x) / (sin7x-sin5x) = (2sin ((7x + 5x) / 2) * cos ((7x5x) / 2) ) / (2sin ((7x-5x) / 2) * cos ((7x + 5x) / 2) = (sin6x * cosx) / (sinx * cos6x) = (tan6x) / tanx = tan6x * cottx
Sin teta / x = cos teta / y sonra sin teta - cos theta =?
Frak { sin teta} {x} = frak {cos teta] {y} ise sin teta - cos theta = pm frak {x - y} {sqrt {x ^ 2 + y ^ 2} frak { sin theta} {x} = frak {cos teta] {y} frak { sin theta} { cos theta} = frak {x} {y} tan teta = x / y ve bitişik y, çünkü cos theta = frak { pm y} {sqrt {x ^ 2 + y ^ 2} sin teta = tan teta cos teta sin teta - cos teta = tan teta cos teta - cos theta = cos teta ( tan teta - 1) = frak { pm y} {sqrt {x ^ 2 + y ^ 2}} (x / y -1) sin teta - cos theta = pm frac {x - y } {sqrt {x ^ 2 + y ^ 2}}
Şunu gösterin, (1 + cos teta + i * sin teta) ^ n + (1 + cos teta - i * sin teta) ^ n = 2 ^ (n + 1) * (cos teta / 2) ^ n * cos ( n * teta / 2)?
Lütfen aşağıya bakın. 1 + costheta + isintheta = r (cosalpha + isinalpha), burada r = sqrt ((1 + costheta) ^ 2 + sin ^ 2theta) = sqrt (2 + 2costheta) = sqrt (2 + 4cos ^ 2 (theta / 2) ) -2) = 2cos (theta / 2) ve tanalpha = sintheta / (1 + costheta) == (2sin (theta / 2) cos (theta / 2)) / (2cos ^ 2 (theta / 2)) = tan (theta / 2) veya alpha = theta / 2 sonra 1 + costheta-isintheta = r (cos (-alfa) + isin (-alfa)) = r (cosalpha-isinalpha) ve yazabiliriz (1 + costheta + isintta) ^ n + (1 + costheta-isintheta) ^ n, DE MOivre teoremini r ^ n (cosnalpha + isinnalpha + cosnalpha-isinnalpha) = 2r ^ ncosnalpha = 2 * 2 ^ ncos ^ n