a) You need to consider `200^o = 180^o + 20^o` , hence you need to use the next formula to evaluate sin `200^o` in terms of k:

`sin (alpha + beta) = sin alpha*cos beta + sin beta*cos alpha`

Plugging `alpha = 180^o` , `beta = 20^o` in the formula yields:

`sin 200^o = sin (180^o + 20^o) = sin 180^o*cos20^o + sin 20^o*cos 180^o`

Plugging sin `180^o = 0` and cos`180^o = -1 ` in the formula yields:

`sin 200^o = - sin 20^o = -k`

b) You need to use the basic trigonometric formula such that:

(The entire section contains 280 words.)

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