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August 20, 2014

August 20, 2014

Posted by **Jat** on Thursday, February 16, 2012 at 4:25am.

a) At what speed alvin travels

b) Find the direction of travel of the two people and hence the angle between their path

c) Find the position vector OA and OB at t sesonds, and hence the vector AB at that time

d)Find the value of t for which the dtring become taut

- Advanced Maths (Vectors) AQA Level, please help? -
**Damon**, Thursday, February 16, 2012 at 6:41amAlvin speed = sqrt (1^2 + 2^2) = sqrt (5)

tan Alvin = 2/1 so angle Alvin = 63.4 deg

tan Bernard = 1/3 so angle = 18.4

so

angle between = 63.4 - 18.4 = 45 degrees

OA = t i + 2t j

OB = 3t i + t j

AB = 2 t i -1 t j

d = sqrt ( 4t^2 + t^2) = t sqrt (5)

90 = t sqrt 5

t = 40.3 seconds

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