Proving perpendicular vectors using Dot Product

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crayzwalz
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Homework Statement



Geometry diagram of a circle with centre O and a chord LM passing through its midpoint A, with labels L, M, O and A.


Homework Equations



dot product a.b = lal.lblcostheta
vectors are perpendicular when a.b = 0

The Attempt at a Solution



OA . LA = 0
OA = OM + MA
LA = LO + OA

OA . LA = (OM+MA) . (LO + OA)
= OM.LO + OM.OA + MA.LO + MA.OAi get stuck here
 
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Look at this image and try this, the notation is a little easier.

Geometric diagram: a circle with a chord from left to bottom-right drawn dotted, and two vectors from a point inside the circle labeled R and S, with A and V marked as a vector sum and difference along the chord.


See if you can show A = (1/2)(S-R) and V = (1/2)(S+R)

Once you do that see if you can show A dot B = 0.