Isidro L. answered • 05/25/19
AP Calculus AB /Algebra Teacher 20 years Experience.
1. In this problem the angle -3Π/4 was proved, notice that the single is negative angle and rotate clockwise ( in the direction of the clock's hands.
2 Another thing that you have to pay attention is that this angle -3Π/4 = - 135°, to draw this angle you need to start at 0° or and move backward or in the direction of the clock's hands until you reach -135°.
Negative 135° is in the third quadrant and the tangent and cotangent are both positive in the third quadrant.
3. Now -3Π/4 is in the same terminal side of 5Π/4. Let find the cotangent of 5Π/4, suing the exact value in the unit circle which is neg square root of 2/ 2 divided by neg square root of 2/2 and I got 1. Therefore the
Cot (-3Π/4) =1 or cosine /sine. or x/y.
In order to visualize this problem better my recommendation for you is to get a copy of the unit circle because the problem stated "exact value", meaning use the radical form of the unit circle.
