Okay, so seing as I missed a bunch, I got myself completely lost. So I somewhat understand what we learned this week. Umm.. I understand all of the first part of 10-1. I think it is the addition and subtraction properties. After that, I get lost, especially with 10-3. I understand that you are supposed to plug a degree in for alpha and convert it back to one of the origional equations, but I do not understand what to do when the degree plugged in for alpha is not on the unit circle or trig chart. I really do not understand much about this section so any help would be much obliged. (:
thanksss
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ok here is an example then:
ReplyDeleteFind the exact value of sin 15degrees
*exact value means you use your trig chart
*think of two numbers from the trig chart can either add or subtract to give you 15
*since it's (45-30), you would look for the formula that uses sin
sin (a-B) = sin a cos B - cos a sin B
* plug #s into equation..
a=45 degrees B=30 degrees
sin (45-30) = sin 45 cos 30 - cos 45 sin 30
sin (a-B) = sin a cos B - cos a sin B
sin (45-30) = sin 45 cos 30 - cos 45 sin 30
sin 15 = (square root of 2 over 2)(square root of 3 over 2) - (square root of 2 over 2)(1/2)
sin 15 degrees = (square root of 6 over 4) - (square root of 2 over 4)
= square root of 6 - square root of 2 all over 4
Amy has this correct but there is also the situation when you cannot just subtract or add two trig chart plug ins to get the answer
ReplyDeletein this type of situation you will have to use the refrence angle steps to complete
remember these are the steps where you plug into
__ sin/cos ___
using the unit circle and quadrent movements