parametrics question (1 Viewer)

sadpwner

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Show that x = a+r cos θ, y = b+r sin θ defines a circle with centre (a, b) and radius r.

How do I form an equation out of this?
 

photastic

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Square x and y and you will cancel out the trig circle identity.
 
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sadpwner

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i tried squaring both sides, but don't really know what to do afterwards. I tried subbing in using the pythag identity tho
 

meggles_

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Yeap



When you get asked a question which has cos or sin, always make them the subject and square them. After squaring them, you add them. Then you use the trig identity, sin squared theta + cos square theta = 1
Super important identity - many trig questions depend on this identity

Pls memorise
 

sadpwner

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lol i knew the identities. I just didn't know you just add trig parametrics together rather than subbing in.
 

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