This is actually really confusing please help me out.

a ball bouncing off a wall

Step-by-step explanation:

Think of it like how if you would flash a flashlight at a mirror it would reflect off of it right? And it would go the opposite way. So it’s like a ball that u throw at a wall because a ball would bounce off the fall going opposite. I hope that makes sense. ^^

Step-by-step explanation:

1-2cos²c.

> (cos²c+sin²c)-2cos²c. (cos²c+sin²c=1)

> cos²c+sin²c-2cos²c

> sin²c-cos²c.

is your correct answer.

hope this helps you.