Question
Find the polar coordinates of each point with the given rectangular coordinates. Use degrees. (-4,-3)
Answers
Damon
r = sqrt (4^2+3^2)
which we know is 5 because of 3 4 5 right triangle so we do not need c^2=a^2+b^2
-4 = 5 cos theta
cos theta = -4/5
theta = 143 if you use your calculator but that would be wrong because we are in QUADRANT 3 where sin and cos BOTH negative
cos^-1 4/5 = 36.9
so theta = 180 + 36.9 = 217 degrees
so
r = 5 , theta = 217
which we know is 5 because of 3 4 5 right triangle so we do not need c^2=a^2+b^2
-4 = 5 cos theta
cos theta = -4/5
theta = 143 if you use your calculator but that would be wrong because we are in QUADRANT 3 where sin and cos BOTH negative
cos^-1 4/5 = 36.9
so theta = 180 + 36.9 = 217 degrees
so
r = 5 , theta = 217