Consider the polar equation r = 2 - 2cos(θ). Complete the table of values for r = 2 - 2cos(θ) at specific angles and sketch the graph using the calculated points.
Solution
To solve this question, let’s first address Part (a) and complete the table for the polar equation r=2−2cos(θ). For each given value of θ, substitute it into the equation to find the corresponding r.
1. Completing the Table
The polar equation is:
r=2−2cos(θ)
We evaluate r at the given values of θ:
For θ=0:
r=2−2cos(0)=2−2(1)=0
For θ=3π:
r=2−2cos(3π)=2−2(21)=2−1=1
For θ=2π:
r=2−2cos(2π)=2−2(0)=2
For θ=32π:
r=2−2cos(32π)=2−2(−21)=2+1=3
For θ=π:
r=2−2cos(π)=2−2(−1)=2+2=4
For θ=34π:
r=2−2cos(34π)=2−2(−21)=2+1=3
For θ=23π:
r=2−2cos(23π)=2−2(0)=2
For θ=35π:
r=2−2cos(35π)=2−2(21)=2−1=1
For θ=2π:
r=2−2cos(2π)=2−2(1)=0
The completed table is:
θ
0
3π
2π
32π
π
34π
23π
35π
2π
r
0
1
2
3
4
3
2
1
0
2. Sketching the Graph
In Part (b), use the table values to plot points in the polar graph. For each pair of (θ,r):
Start at the angle θ and move outward along the radius by r.
Connect the points to form the graph of r=2−2cos(θ).
Let me know if you'd like me to help plot the graph or explain the process further!
Relative Questions:
What is the significance of symmetry in polar graphs?
How does the graph of r=2−2cos(θ) compare to a standard cardioid?
What happens if the coefficient of cos(θ) changes in the equation?
How would the graph look for r=2+2cos(θ)?
Why does r=2−2cos(θ) return to r=0 at 2π?
Tip: In polar graphs, pay attention to symmetry and intercepts for faster plotting!