Question #8a89a

1 Answer
Dec 21, 2016

Use the equations, r = sqrt(x^2 + y^2)r=x2+y2 and theta = pi + tan^-1(y/x)θ=π+tan1(yx)
(-3sqrt(3), -3) to (6, (7pi)/6)(33,3)(6,7π6)

Explanation:

Given the point:

Use the equation:

r = sqrt(x^2 + y^2r=x2+y2

r = sqrt((-3sqrt(3))^2 + (-3)^2)r=(33)2+(3)2

r = sqrt(27 + 9)r=27+9

r = 6r=6

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

"[1] "theta = tan^-1(y/x); x > 0 and y ge 0[1] θ=tan1(yx);x>0andy0
"[2] "theta = pi/2; x = 0 and y > 0[2] θ=π2;x=0andy>0
"[3] " theta = pi + tan^-1(y/x); x < 0[3] θ=π+tan1(yx);x<0
"[4] "theta = (3pi)/2; x = 0 and y < 0[4] θ=3π2;x=0andy<0
"[5] "theta = 2pi + tan^-1(y/x); x > 0 and y < 0[5] θ=2π+tan1(yx);x>0andy<0

Because x = -3sqrt(3)x=33, then we do not care about the value of y and we use equation [3}:

theta = pi + tan^-1((-3)/(-3sqrt(3))); x < 0θ=π+tan1(333);x<0

theta = (7pi)/6θ=7π6