R2(<span>cos2</span>ϕ−<span>sin2</span>ϕ)−2rcosϕ=0<span><span>r2</span>(<span>cos2</span>ϕ−<span>sin2</span>ϕ)−2rcosϕ=0</span>
<span><span><span>r2</span>cos<span>(2ϕ)</span>−2rcosϕ=0</span><span><span>r2</span>cos<span>(2ϕ)</span>−2rcosϕ=<span>0
Now </span></span></span> divide through by <span><span>r≠0</span><span>r≠0</span></span>
and get
<span><span>rcos<span>2ϕ</span>−2cosϕ=0</span><span>rcos<span>2ϕ</span>−2cosϕ=0</span></span>
or
<span><span>r=2<span><span>cosϕ</span><span>cos<span>2ϕ</span></span></span></span><span>r=2<span><span>cosϕ</span><span>cos<span>2<span>ϕ</span></span></span></span></span></span>
Answer:c.
Step-by-step explanation:
Solve for y
let's put our equation first
Flip the equation
Now follow the rule of 
_________________________
_________________________
add 
to both sides
Divide both sides by 
would equal 
Answer:
Choice C
Step-by-step explanation:
Divide both sides by -3.55; remember that by dividing both sides of an inequality by a negative sign, you need to change the direction of the inequality sign.
Answer: Choice C
Volume =πr²h
192π = πr²(12) // Plug the value of the volume and the height in
r² = 192π ÷ 12π // divide by 12π on both sides
r² = 16 // Simplify
r = √16 // square root both sides
r = 4
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Answer: The radius is 4 cm.
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