Malorie's holiday blog #4

I'm Reviewing 10.1

we weren't allowed to use calculators and we had to know the trig chart . . .
In order to do this you must know these formulas:

cos(alpha +/- beta)= cos(alpha)cos(beta) -/+ sin(alpha)sin(beta)

sin(alpha +/- beta)= sin(alpha)cos(beta) +/- cos(alpha)sin(beta)

Alpha and beta will come from the trig chart. You will either add or subtract them to get the angle needed.

Ex: find the exact value of sin15 degrees.

alpha= 45
beta= 30

45-30 = 15

sin(45-30)= (sin 45)(cos 30) - (cos 45)(sin 30)

=(square root of 2/2)(square root of 3/2) - (square root of 2/2)(1/2)

square root of 6/4 - square root of 2/4 = square root of 6 - square root of 2/4

sin 15= square root of 6 - square root of 2/4