Answer:
Step-by-step explanation:
sin=y/r
cos=x/r
sin=21/29
cos=x/29
x^2+y^2=r^2
x^2+21^2=29^2
x^2+441=841
x=sqrt(841-441)
x=20
cos=20/29
Only |
sin + | All Positive
---------------------|-------------------
only | Only cos +
tan + |
Answer:
C
Step-by-step explanation:
Using the trigonometric identity
sin²x + cos²x = 1 ⇒ cosx = ± [tex]\sqrt{1-sin^2x}[/tex]
Given
sinx = [tex]\frac{21}{29}[/tex], then
cosx = [tex]\sqrt{1-(\frac{21}{29})^2 }[/tex] ( positive since 0 < x < 90 )
= [tex]\sqrt{1-\frac{441}{841} }[/tex]
= [tex]\sqrt{\frac{400}{841} }[/tex] = [tex]\frac{20}{29}[/tex]
