Question

Sin 285°
+ sin ? 88 tsin? lot sin?​

Answer 1

Answer:

please follow me.....

......

Answer 2

Step-by-step explanation:

Trig unit circle -->

sin 285 = sin (-75 + 360) = sin (-75)

Property of complementary arcs -->

sin (-75) = sin (-15 + 90) = - cos 15

Next, find (cos 15) by using trig identity:

2cos2a=1+cos2a

2cos2(15)=1+cos30=1+√32=2+√32

cos215=2+√34

cos15=±√2+√32

Since cos 15 is positive then take the positive value only.

Finally:

sin 285 = - cos 15 = −√2+√32

Check by calculator:

sin 285 = - 0.965

−√2+√32=1.932=−0.965. OK