Question
how do you find the standard form of
7(cos255degrees + isin255degrees) ?
7(cos255degrees + isin255degrees) ?
Answers
Reiny
we need cos 225° and sin225°
225 = 180+45 , it is in quadrant III and has the same numerical trig values as 45°, but in III both the sine and cosine are negative
sin 225 = - sin 45° = -1/√2
cos 225 = - cos 45° = -1/√2
so 7(cos255degrees + isin255degrees)
= 7(-1/√2 - i (1/√2))
= -7/√2 - (7/√2) i
225 = 180+45 , it is in quadrant III and has the same numerical trig values as 45°, but in III both the sine and cosine are negative
sin 225 = - sin 45° = -1/√2
cos 225 = - cos 45° = -1/√2
so 7(cos255degrees + isin255degrees)
= 7(-1/√2 - i (1/√2))
= -7/√2 - (7/√2) i
Steve
now, just change all those 225's to 255's and redo the calculations.