Answer:
the answer is actually study and you would know
Step-by-step explanation:
1. 90 2. 8000 3. 500 4. 200,000
5cos (2x)+7=cos (2x)+8, 4cos (2x)=1, cos (2x)=1/4, 2x=arccos(1/4), x=(1/2)arccos (1/4). I used x instead of theta, and arccos is cos inverse
