Question

Please help me with this question

Answer 1

Answer:

cos(2x) = (-527/625)

Step-by-step explanation:

Check out my work in the attachment as you read these steps:

1. Use the given trig. function to draw a triangle and mark the sides with the correct lengths. Note the given domain of the angle to get quadrant. Here it is in quadrant 1, so all sides are positive.
2. Find the unknown side just to save time down the road. You can use the pythagorean theorem for this.
3. With all sides of the triangle found, apply it to the function you want to find. (Note that this angle is "x", which is not the same as "2x". You'll have to use the Double Angle Identity for cosine here; though you could need other identities at other times.)