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You must think of the unit circle.

negative theta is in either radians or degrees and represents a specific area on the unit circle. Remember the unit circle is also like a coordinate plane and cos is the x while sin is the y coordinate. Here is an example:

cos(-45): The cos of negative 45 degrees is pi/4 and cos(45) is also pi/4

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Q: Why does cos negative theta equals positive theta?
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Continue Learning about Trigonometry

How do you find tan-theta when sin-theta equals -0.5736 and cos-theta is greater than 0?

-0.5736


Given tan Theta equals negative 15 divided by 8 and 90 degrees is less than or equal to theta which is less than or equals to 180 state 5 other trigonometric ratios and determine the measure of theta?

sin(theta) = 15/17, cosec(theta) = 17/15 cos(theta) = -8/17, sec(theta) = -17/8 cotan(theta) = -8/15 theta = 2.0608 radians.


Is the cosine function an odd function?

No. Cosine, along with sec, is an even function. The odd functions are sin, tan, csc, and cot. The reason for this is because is you take the opposite of the y-value for the cosine function, the overall value of the function is not affected.Take, for example, cos(60 degrees), which equals POSITIVE 1/2.If you flip it over the x-axis, making the y's negative, it becomes cos(-60 degrees), or cos(300 degrees). This equals POSITIVE 1/2.Now let's look at an odd function. For example, sin(30 degrees) equals POSITIVE 1/2. Now take the opposite of this.sin(-30 degrees), or sin(330 degrees), equals NEGATIVE 1/2. This is because it is found in the fourth quadrant, where the y's are negative. Sine of theta, by definition, is y divided by r. If y is negative, sine is negative.


If cos and theta 0.65 what is the value of sin and theta?

You can use the Pythagorean identity to solve this:(sin theta) squared + (cos theta) squared = 1.


What is cos 360 minus theta?

Cos(360 - X) = Trig. Identity Cos(360)Cos(x) + Sin(360)Sin(x) => 1CosX + 0Sinx => CosX + o => CosX