# Thread: another intro to circular functions question.

1. ## another intro to circular functions question.

find the value of theta to the nearest second.

- sin theta= -0.4545 and theta is in the 4th quadrant

-sec theta= 2/3 and theta is in the 1st quadrant

2. Originally Posted by Dave19
find the value of theta to the nearest second.

- sin theta= -0.4545 and theta is in the 4th quadrant

-sec theta= 2/3 and theta is in the 1st quadrant
Here, a calculator must be used.

sin(theta) = -0.4545
So, theta = arcsin(-0.4545)
By calculator, theta = -27 degees.
That is if theta were meausured counterclockwise as usual.

The negative then means theta should be measured clockwise. Then theta will fall in the 4th quadrant.
Theta then = 360 -27 = 333 degrees. ....in the usual, counterclockwise, measuring.

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sec(theta) = 2/3

In a calculator, there are no sec or arcsec functions. Only cos or arccos functions.
So convert the sec into cos first so that you can use the calculator.

sec = 1/cos
So, cos = 1/sec

cos(theta) = 1/(2/3) = 3/2 = 1.5
Cannot be.
The maximum value of cos is only 1.0

The question is wrong.