Oblicz wartośc wyrażenia
a) sin alfa +cos alfa wiedzac ze sin alfa=2/3
b)sin do kwadratu alfa -cos do kwadratu alfa wiedzac ze cos alfa=1/5
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sinα= y/r=2/3
cos α= x/r=(√5)/3
x^2+y^2=r^2
x^2+2^2=3^2
x^(2 )= 9-4
x^(2 )=5
X= √5
sinα + cos α= 2/3+√5/3 = (2+√5)/3
b)
sinα= y/r=(√24)/5
cosα= x/r=1/5
x^2+y^2=r^2
y^2+1^2=5^2
y^2=25-1
y= √24
〖sinα〗^2-〖cosα〗^2= (〖(√24)/5)〗^2 –(〖1/5)〗^2= 24/25-1/25=23/25