This week we went over out study guides for the exam, took the exam on Wednesday, and went over Chapter 10-Section 1 on Friday.
10.1 is a pretty easy section. the only difficult part is applying the trig chart. Since we cannot use calculators, we are relying completely on our minds and the trig chart.
The formulas we need to know are:
cos(alpha)+-(beta)=cos(alpha)cos(beta)-+sin(alpha)sin(beta)
sin(alpha)+-(beta)=sin(alpha)cos(beta)+-cos(alpha)sin(beta)
It is a long formula but it is easy to work out.
EXAMPLE #1
Find the exact value of sin15
to find this, you have to find two trig chart angles that add or subtract to give you 15.
(alpha)45-(beta)30=15
now, plug it into the sin formula
sin(45-30)=sin45cos30-cos45sin30
(sq.root2/2)(sq.root3/2)-(sq.root2/2)(1/2)
=(sq.root6/2)-(sq.root2/4)
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