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Trigonometry

1)If sin(t) = -5/13 and 270 degrees is less than or
equal to t and is less than or equal to 360 degrees,
then cos(t)=?

2)If 0 degrees is less than t and less than 90 degrees
and cos(t) = 4/5, then cos(2t)=?

3)A right triangle is shown, sec(t) =? . |
1 = hypotenuse . |
x = y side of triangle . | x
t = inside angle < t___________|

Solution Preview

1) Using that cos^2+sin^2=1 we get: cos(t)^2=1-25/169=144/169=(12/13)^2 so cos(t)=12/13 or cos(t)=-12/13. Because t is in the fourth quarter, cos(t) ...

Solution Summary

This shows how to work with trigonometric functions and angles.

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