Jika sin a = 4/5 dan sin b = 24/25 a dan b terletak di kuadran II maka nilai sin (a-b) adalah......
narifa
Di kuadran 2, sin bernilai positif, cos bernilai neatif sin a = depan /miring = 4/5 samping = √(5² - 4²) = 3 cos a = - (samping / miring) = - 3/5
sin b = depan/miring = 24/25 samping = √(25² - 24²) = 7 cos b = - (samping/miring) = - 7/25
sin (a-b) = sin a cos b - cos a sin b sin (a-b) = (4/5) (-7/25) - (-3/5) (24/25) sin (a-b) = 44/125
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whongaliem
Sin² A + cos² A = 1 + cos² A = 1 + cos² A = 1 cos² A = 1 - cos² A = cos A = cos A = - atau cos A = karena A di kuadra II maka cos A = sin² B + cos² B = 1 + cos² B = 1 + cos² B = 1 cos² B = 1 - cos² B = cos B = cos B = - atau cos B = karena B di kuadran II maka cos B = - sin (A - B) = sin A .cos B - .cos A .sin B = . - . = + =
sin a = depan /miring = 4/5
samping = √(5² - 4²) = 3
cos a = - (samping / miring) = - 3/5
sin b = depan/miring = 24/25
samping = √(25² - 24²) = 7
cos b = - (samping/miring) = - 7/25
sin (a-b) = sin a cos b - cos a sin b
sin (a-b) = (4/5) (-7/25) - (-3/5) (24/25)
sin (a-b) = 44/125
+ cos² A = 1
+ cos² A = 1
cos² A = 1 -
cos² A =
cos A =
cos A = - atau cos A =
karena A di kuadra II maka cos A =
sin² B + cos² B = 1
+ cos² B = 1
+ cos² B = 1
cos² B = 1 -
cos² B =
cos B =
cos B = - atau cos B =
karena B di kuadran II maka cos B = -
sin (A - B) = sin A .cos B - .cos A .sin B
= . - .
= +
=