dylan's 10.1 blogs :D

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10.1

In 10.1 we learned how to find exact value without calculators. All of the problems are either simplifying or using the trig chart to simplify.

formulas:

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

example:

find exact value of sin 15 degrees
(use two degree values from the trig chart to add or subtract to give you 15, so 45-30=15
alpha=45 beta=30
we will use the sin formula because the problem is sin 15 degrees
sin(45-30)=sin(45)cos(30)-cos(45)sin(30)
sin 15=(√2/2)(√3/2)-(√2/2)(1/2)
=cos 75 = (√6-√2)/4

remember, alpha and beta come from the trig chart.