# math

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theta is a first quadrant angle in standard position and cos theta = 1/(sqrt10) .

Find the exact value of sin theta,

• math -

(sin theta)^2+(cos theta)^2=1;
(sin theta)^2+1/10=1;
(sin theta)^2=9/10

sin theta= 3/(sqrt10)
OR
sin theta=-3/(sqrt10)

But since theta is a first quadrant angle
==> sin theta is positive

Therefore, sin theta= 3/(sqrt10)

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