Question

1. Se stie ca 0° < u < 90° si cos u = 4 / 5.
a) sin u = ... ;
b) ctg ( 90° - u ) = ....;
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Answer 1

a)teorema,fundam,a,trigonometriei,zice,ca,sin,patrat,de,a+cos,patrat,de,a=1
daca,avem,cos,u=4/5=>sin,patrat,u+16/25=1=>
sin,patrat,de,u=1-16/25=>sin,patrat,de,u=9/25=>sin,u=3/5
b)ctg(90-u)=tg,u