I’m a senior in high school and I don’t know how to choose sin or cos in physics problem. For the most part I memorised them. For example, why is the flux of a magnetic field = BAcos(angle) and why is the electromagnetic force = ILBsin(angle).
The last two years weren’t normal as we studied online so it’s highly appreciated if someone can eli5 and fill in the gaps for me.
In: 4
Go back to the original diagrams of right-angled triangles where you first learned about trigonometry functions. Sin = opposite side over hypotenuse, cos equals adjacent side over hypotenuse.
Formulas are usually in the form X = K.trig(angle) where K is something you know, B*A in the first example. You need to find out X which is in a direction at some angle to K so draw a diagram where K is the hypotenuse and work out whether the X you want is opposite or adjacent the the angle you know.
Another way is to remember that sine is zero at 0 and 180 degrees (π radians) and maximum at 90 and 270. Cosine is opposite. So does your X increase or decrease as the angle changes from the direction of X being aligned with K to being at right angles to it?
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