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
Answer:
Yes, it is a terminating decimal.
Step-by-step explanation:
3.14 ends and it does not repeat. If it repeated, it would be a repeating decimal but since it does not, it is a terminating decimal.
X+3 and y=5
Let’s start with finding X
5x+3y=30
5x+3(5x-10)=30
20x-30=30(simplified)
20x-30+30=30+30(+30 to each side)
20x=60(divide by 20)
20x/20 60/20
X=3
Now to Y
Y=5x-10
Y=(5)(3)-10
Y=5 (simplified)