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:
Step-by-step explanation:
what?
Length of AB is 18
Step-by-step explanation:
- Step 1: Find length of AB when AC = 9√3 and ∠B = 60°. Use trigonometric ratio sine.
sin 60 = opposite side/hypotenuse = 9√3/x
x = 9√3/sin 60
= 9√3/√3/2 = 9√3 × 2/√3 (∵ a ÷ b = a×1/b)
= 18
1.41666666667 is the answer