Jessica uses a 20% off coupon when she buys a new camera. The original price of the camera was $150. How much money does Jessica
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Two angles are said to be supplementary if their sum is 180 degrees. So, if x and y are supplementary angles, the formula is
We know that one of the angles (say x) is 98. So, the equation updates to
If we want to solve for the other angle, we can simply subtract 98 from both sides to get
Answer: see proof below
<u>Step-by-step explanation:</u>
Given: cos 330 =
Use the Double-Angle Identity: cos 2A = 2 cos² A - 1
Proof LHS → RHS:
LHS cos 165
Double-Angle: cos (2 · 165) = 2 cos² 165 - 1
⇒ cos 330 = 2 cos² 165 - 1
⇒ 2 cos² 165 = cos 330 + 1
Given:
Divide by 2:
Square root:
Scratchwork:
Since cos 165 is in the 2nd Quadrant, the sign is NEGATIVE
LHS = RHS
