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# Modulus & Perpendicular Vectors and arrgghh! watch

1. Question 9

The two vectors a and b are perpendicular. If a has magnitude 8 and b has magnitude 3 what is |a2b|?

Only the 1st week of Uni, and this maths is already puzzling me!

Thanks!

Edit:

Nevermind - in my maths-panic I posted in totally the wrong forum, and figured out the answer (10 units) anyway!

2. (Original post by PhysicsGal)
Question 9

The two vectors a and b are perpendicular. If a has magnitude 8 and b has magnitude 3 what is |a2b|?

Only the 1st week of Uni, and this maths is already puzzling me!

Thanks!

Edit:

Nevermind - in my maths-panic I posted in totally the wrong forum, and figured out the answer (10 units) anyway!

USe the Pythagorean theorem
THe two legs |a|=8 and |2b|=6, the hypotenuse is |a-2b| according the
definition of

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