Answer:
Standard Complex Form : [tex]-\frac{25\sqrt{3}}{2}+\frac{25}{2}i[/tex]
Step-by-step explanation:
We want to rewrite this expression in standard complex form. Let's first evaluate cos(5π / 6). Remember that cos(x) = sin(π / 2 - x). Therefore,
cos(5π / 6) = sin(π / 2 - 5π / 6),
π / 2 - 5π / 6 = - π / 3,
sin(- π / 3) = - sin(π / 3)
And we also know that sin(π / 3) = √3 / 2. So - sin(π / 3) = - √3 / 2 = cos(5π / 6).
Now let's evaluate the sin(5π / 6). Similar to cos(x) = sin(π / 2 - x), sin(x) = cos(π / 2 - x). So, sin(5π / 6) = cos(- π / 3). Now let's further simplify from here,
cos(- π / 3) = cos(π / 3)
We know that cos(π / 3) = 1 / 2. So, sin(5π / 6) = 1 / 2
Through substitution we receive the expression 25( - √3 / 2 + i(1 / 2) ). Further simplification results in the following expression. As you can see your solution is option a.
[tex]-\frac{25\sqrt{3}}{2}+\frac{25}{2}i[/tex]
