If
Then prove that:
Please help me!

 see proof below

Step-by-step explanation:

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: idk

step-by-step explanation:

center (1,3) with radius 6

step-by-step explanation:

we must complete the square to find the center and radius of the circle.

first make sure the x and y squared terms have 1 as their coefficients. we also make sure x and y terms together.

we now create space between the x and y terms with parenthesis.

we complete the square by taking the middle terms -2x and the -6y - divide each and square them.

we add the squares to both sides.

simplify.

and write the quadratics in factored form.

the center is (h,k) or (1,3). the radius is the square root of 36 which is 6.