How do you evaluate e^( ( pi)/2 i) - e^( ( 23 pi)/3 i)eπ2ie23π3i using trigonometric functions?

1 Answer
Dec 17, 2016

With the help of Euler's formula we can take this right down to
0.5 + ii (1 + (sqrt3)/232)

Explanation:

Start with Euler's formula: e^(ix)eix = cos x + i Sin xcosx+isinx

Your expression becomes:

cos pi/2π2 + ii sin pi/2π2 - cos (23pi)/323π3 - ii sin (23pi)/323π3

To simplify, note cos pi/2π2 = 0, sin pi/2π2 = 1

and since each complete revolution of a unit circle is 2piπ, which we will write as (6pi)/36π3, cos (23pi)/323π3 = cos (5pi)/35π3
and likewise for sin (23pi)/323π3 = sin (5pi)/35π3

So, we now have the original expression simplified down to

ii - cos (5pi)/35π3 - ii sin (5pi)/35π3

where cos (5pi)/35π3 = 0.5 and sin (5pi)/35π3 = - (sqrt3/2)(32)

So, finally, the result is

0.5 + ii (1 + (sqrt3)/232)