2.3 i think let me know if it works
Your answer would be A 1040.
1 and 4 will be the expression that makes the equatio. true for all values of x to prove i have done it in the picture attached in this message
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 
There are 30 days in April.
If 18 days had rain, it means 12 didn't.
18/30=x/100
Make sure both fractions can be made into fractions with a denominator of 100:
180/300=x/100
Divide 180/300 by 3:
60/100=x/100
This shows that the 18 days that did rain take up 60% of the whole month.
So then the remaining 12 days that didn't have rain must take up 40% of the month.
Solution:
40% of the days did not have rain during the month of April