If the axes are rotated through an angle 45 ° , the coordinates of the point ( 2 2 , - 3 2 ) in the new…

If the axes are rotated through an angle 45°, the coordinates of the point (22,-32) in the new system are
  1. (33,5)
  2. (1,5)
  3. (53,7)
  4. (7,3)

Solution

If the coordinate axes are rotated through an angle θ, then a point P(x, y) will have co-ordinate P(x', y')

Where x'=xcosθ+ysinθ and y'=ycosθ-xsinθ

Here, x, y=22, -32 and θ=45°

Now, x'=22cos45°-32sin45°

x'=22×12-32×12

x'=2-3=-1

And, y'=-32cos45°-22sin45°

y'=-32×12-22×12

y'=-3-2=-5

Therefore the coordinates of the given point in the new system is -1, -5

Asked in: AP EAMCET 2021 (19 Aug Shift 1)

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