The polar equation r = - 4 · cos θ is equivalent to the equation of the circle (x + 2)² + y² = 2², whose radius is 2 and center is (h, k) = (- 2, 0).
<h3>How to transform a polar expression into its rectangular form</h3>
Polar and rectangular forms are related by this relation: (x, y) → (r · cos θ, r · sin θ), where r is the radial distance with respect to the origin and θ is the angle in standard position. We can use this fact to change the given expression into its rectangular form:
r = - 4 · (x / r)
r² = - 4 · x
x² + y² = - 4 · x
y² = - (x² + 4 · x)
y² - 4 = - (x² + 4 · x + 4)
y² - 4 = - (x + 2)²
(x + 2)² + y² = 4
(x + 2)² + y² = 2²
In a nutshell, the polar equation r = - 4 · cos θ is equivalent to the equation of the circle (x + 2)² + y² = 2², whose radius is 2 and center is (h, k) = (- 2, 0).
To learn more on polar equations: brainly.com/question/27341756
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Answer:
Circumference of semi circle = 116 cm
Step-by-step explanation:
Given:
Diameter of a circle = 28 cm
Find:
Circumference of semi circle
Computation:
Circumference of semi circle = πr + Diameter
Circumference of semi circle = (22/7)(28) + 28
Circumference of semi circle = 88 + 28
Circumference of semi circle = 116 cm
Rewrite in quadratic form:
x² + 13x + 4 = 0
The best approximations, given the options, are 0 and -13
The actual solution is -0.3 and -12.7
Answer:
C.-75
Step-by-step explanation:
15=-x/5
(15)*(5)=-x
75=-x
x=(-1)*75=-75