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  1. AP Pre Calculus
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Convert (3, π/6) from polar to Cartesian coordinates.

x = 3cos(π/6) = 3√3/2, y = 3sin(π/6) = 3/2

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Convert (3, π/6) from polar to Cartesian coordinates.

x = 3cos(π/6) = 3√3/2, y = 3sin(π/6) = 3/2

Convert (-1, 1) from Cartesian to polar coordinates.

r = √( (-1)² + 1²) = √2, θ = tan⁻¹(1/-1) = -π/4 + π = 3π/4

Find an equivalent polar coordinate representation for (2, π/2) with a negative 'r'.

(-2, π/2 + π) = (-2, 3π/2)

Convert the complex number 1 + i to polar form.

r = √(1² + 1²) = √2, θ = tan⁻¹(1/1) = π/4. Polar form: √2(cos(π/4) + i sin(π/4))

Convert the polar coordinate (4, 5π/3) to cartesian coordinates.

x = 4cos(5π/3) = 2, y = 4sin(5π/3) = -2

Convert the cartesian coordinates (0, -5) to polar coordinates.

r = √(0² + (-5)²) = 5, θ = 3π/2

Represent the polar coordinate (6, π/4) with an angle between 2π and 4π.

(6, π/4 + 2π) = (6, 9π/4)

If z = 3(cos(π/6) + i sin(π/6)), find z in the form a + bi.

z = 3(√3/2 + i(1/2)) = (3√3/2) + (3/2)i

If z = -2 + 2i, find z² in the form a + bi.

z² = (-2 + 2i)² = 4 - 8i - 4 = -8i

Express the complex number z = 5(cos(π) + i sin(π)) in cartesian form.

z = 5(-1 + i(0)) = -5

Define polar coordinates.

Coordinates defined by a distance (r) from the origin and an angle (θ) from the positive x-axis.

What is the pole in polar coordinates?

The origin (0,0) in the polar coordinate system.

Define the polar axis.

The positive x-axis in the polar coordinate system, used as the reference for measuring angles.

What does 'r' represent in polar coordinates?

The radial distance from the pole to the point.

What does 'θ' represent in polar coordinates?

The angle measured counterclockwise from the polar axis.

Define a complex number.

A number of the form a + bi, where 'a' and 'b' are real numbers, and i is the imaginary unit (√-1).

What is the imaginary unit 'i'?

i = √-1

What is the complex plane?

A plane where the x-axis represents the real part of a complex number, and the y-axis represents the imaginary part.

Define the magnitude (or modulus) of a complex number.

The distance from the origin to the point representing the complex number in the complex plane.

Define the argument (or angle) of a complex number.

The angle between the positive real axis and the line connecting the origin to the complex number in the complex plane.

Formula to convert polar to Cartesian coordinates (x)?

x=r⋅cos(θ)x = r \cdot cos(\theta)x=r⋅cos(θ)

Formula to convert polar to Cartesian coordinates (y)?

y=r⋅sin(θ)y = r \cdot sin(\theta)y=r⋅sin(θ)

Formula to convert Cartesian to polar coordinates (r)?

r=x2+y2r = \sqrt{x^2 + y^2}r=x2+y2​

Formula to convert Cartesian to polar coordinates (θ)?

θ=tan−1(y/x)\theta = tan^{-1}(y/x)θ=tan−1(y/x) (Adjust quadrant!)

Polar form of a complex number?

r(cosθ+isinθ)r(cos \theta + i sin \theta)r(cosθ+isinθ)

How to find 'r' from a complex number a+bi?

r=a2+b2r = \sqrt{a^2 + b^2}r=a2+b2​

How to find 'θ' from a complex number a+bi?

θ=tan−1(b/a)\theta = tan^{-1}(b/a)θ=tan−1(b/a) (Adjust quadrant!)

How to represent the same point with a negative 'r'?

(r,θ)=(−r,θ+π)(r, \theta) = (-r, \theta + \pi)(r,θ)=(−r,θ+π)

How to represent the same point with coterminal angles?

(r,θ)=(r,θ+2πk)(r, \theta) = (r, \theta + 2\pi k)(r,θ)=(r,θ+2πk)

What are the equivalent cartesian coordinates when r = 2 and θ = 7π/6?

x=2cos(7π/6)=−√3x = 2cos(7π/6) = -√3x=2cos(7π/6)=−√3, y=2sin(7π/6)=−1y = 2sin(7π/6) = -1y=2sin(7π/6)=−1