SOLUTION: What is the value of sin210 cos30 - cos210 sin30? Is it 0? If not what is it and how do i find the answer?

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Question 457184: What is the value of sin210 cos30 - cos210 sin30?
Is it 0? If not what is it and how do i find the answer?
Answer by bucky(2189) About Me  (Show Source):
You can put this solution on YOUR website!
Don't let the trigonometric functions confuse you. Since you are given the angles that each function is operating on, you just need to realize that there are four numbers involved. You can either use your knowledge of the triangles that represent these angles to determine the ratios or you can use a scientific calculator to look them up.
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Specifically from a calculator:
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sin(210) = -0.5
cos(30) = +0.8660
cos(210) = -0.8660
sin(30) = +0.5
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Substitute these values into the given expression sin210 cos30 - cos210 sin30 and you get:
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[(-0.5)*(+0.8660)] - [(-0.8660)*(+0.5)]
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Multiply out each of the two terms to get:
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[-0.4330] - [-0.4330]
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Remove the brackets. Note that for the second term the minus sign in front of the brackets will change the sign of the number inside the brackets when the brackets are removed and the result is:
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-0.4330 + 0.4330
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And you are correct, the answer is zero.
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Hope this gives you a little more confidence in what you are doing.