Question #8a89a

1 Answer
Dec 21, 2016

Use the equations, r = sqrt(x^2 + y^2) and theta = pi + tan^-1(y/x)
(-3sqrt(3), -3) to (6, (7pi)/6)

Explanation:

Given the point:

Use the equation:

r = sqrt(x^2 + y^2

r = sqrt((-3sqrt(3))^2 + (-3)^2)

r = sqrt(27 + 9)

r = 6

There are many equations for the angle, theta; which one you use depends on x and y:

"[1] "theta = tan^-1(y/x); x > 0 and y ge 0
"[2] "theta = pi/2; x = 0 and y > 0
"[3] " theta = pi + tan^-1(y/x); x < 0
"[4] "theta = (3pi)/2; x = 0 and y < 0
"[5] "theta = 2pi + tan^-1(y/x); x > 0 and y < 0

Because x = -3sqrt(3), then we do not care about the value of y and we use equation [3}:

theta = pi + tan^-1((-3)/(-3sqrt(3))); x < 0

theta = (7pi)/6