Which sum or difference identity could be used to prove that sin(π + q) = -sin q

is an identity?

we should know that :

sin ( a + b ) = sin a * cos b + sin b cos a

For the given equation :

sin (π + q) = sin π * cos q + sin q * cos π

sin π = zero and cos π = -1

∴ sin (π + q) = 0 * cos q + sin q * (-1) = - sin q

Another solution:

The angle (π + q) lies in the third quarter ⇒ (1)

(π + q) and (-q) are supplementary angles ⇒ (2)

From (1) and (2)

sin(π + q) = -sin q

they charge the same amount at 20 minutes.

step-by-step explanation:

she will sew have sewn five dresses   and be 1/3 done with the sixth one in an hour.

step-by-step explanation:

3/4 of an hour=45 mins

lucy makes 1 dress per 11.25 minutes

45 mins+11.25 mins=56.25 mins

60 mins- 56.25 mins=3.75 mins

3.75 mins is 1/3 of of 11.25 mins

therefore she the other 1/3 would be part of the hour and she will have sewn 5 dresses and begun the sixth.

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