Question

How do you perform the operation in trigonometric form `(5/3(cos(140)+isin(140)))(2/3(cos(60)+isin(60)))`?

Answer 1

`(5/3(cos140^@+isin140^@))(2/3(cos60^@+isin60^@))=10/9(cos200^@+isin200^@)`

Explanation:

`(5/3(cos140^@+isin140^@))(2/3(cos60^@+isin60^@))`

= `10/9[cos140^@cos60^@+icos140^@sin60^@+isin140^@cos60^@+i^2sin140^@sin60^@]`

= `10/9(cos140^@cos60^@-sin140^@sin60^@+icos140^@sin60^@+isin140^@cos60^@]`

= `10/9(cos(140^@+60^@)+isin(140^@+60^@))`

= `10/9(cos200^@+isin200^@)`