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Introductory Physics Homework Help
Finding the angle given positive x component and negative y component
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[QUOTE="collinsmark, post: 4506457, member: 114325"] As a heads up though, for future problems, you might want to get into the habit of actually plotting the vectors out. You can't blindly trust the inverse trigonometric functions on your calculator, as they can mislead you. For example, suppose [I]A[/I][SUB]x[/SUB] was -3 m instead of positive 3 m. The angle you first calculate is [I]θ[/I] = ATAN(-4/-3) = 53[SUP]o[/SUP]. The angle you calculate is positive, but you can tell when graphing the vector that not only is the angle negative, but it also is in the third quadrant. In that case you need to subtract 180[SUP]o[/SUP] from the result. So in that case the angle would be 53[SUP]o[/SUP] - 180[SUP]o[/SUP] = -127[SUP]o[/SUP]. ------------------------------------------- As another example, suppose that the signs of both were opposite what you were given, [I]A[/I][SUB]x[/SUB] = -3 [I]A[/I][SUB]y[/SUB] = 4 The angle you calculate with the ATAN function gives you -53[SUP]o[/SUP] again (this is the same result as in the original problem). But you can tell by graphing the function that its in the second quadrant. So now you need to add 180[SUP]o[/SUP] to it, making it the correct +127[SUP]o[/SUP]. [/QUOTE]
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Introductory Physics Homework Help
Finding the angle given positive x component and negative y component
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