z = r(cos ß + i(sin ß))
where r = √(x^2+y^2)
cos ß = x/r and sin ß = y/r
your z = -7 + 4i
so r = √65, which you had correctly done
cos ß = -7/√65 and sin ß = 4/√65
the angle in standard position is 29.7┼
the quadrant where the cosine is negative and the sine is postitive is the second quadrant
so ß = 180 - 29.7 = 150.26º
so -7+4i = √65(cos 150.26 + i(sin 150.26)
find the trigonometric form of the following number:
-7 + 4i
I keep getting the wrong answer for these questions.
mine was:
square root of 65 (cos330.255 degrees + sin330.255i degrees)
1 answer
2 answers