Question Details

The position vector of point P (20, 10) is rotated anti-clockwise in X-Y plane by an angle 6 =30° such that point P occupies position Q, as shown in the figure. The coordinates (x, y) of Q are 

Options

A

(13.40,22.32)

B

(22.32,8.26)

C

(12.32,18.66)

D

(18.66,12.32)

Correct Answer :

(12.32,18.66)

Solution :

The correct option is (12.32, 18.66).

Step-by-Step Explanation:

When a point P(x,y) is rotated counter-clockwise (anti-clockwise) about the origin by an angle θ in the 2D Cartesian plane, its new coordinates Q(x',y') are determined using the standard rotation transformation equations:


x' = x cos ( θ ) y sin ( θ )


y' = x sin ( θ ) + y cos ( θ )

From the problem statement and the provided figure:
- The initial point is P(20,10), so we have x=20 and y=10.
- The angle of anti-clockwise rotation is θ=30ˆ.

Let us calculate the trigonometric values for θ=30ˆ:
- sin(30ˆ)=0.5
- cos(30ˆ)=320.8660

1. Calculating the new x-coordinate (x'):


x' = 20 · cos ( 30ˆ) 10 · sin ( 30ˆ)


x' = 20 · 0.8660 10 · 0.5


x' = 17.32 5.00 = 12.32

2. Calculating the new y-coordinate (y'):


y' = 20 · sin ( 30ˆ) + 10 · cos ( 30ˆ)


y' = 20 · 0.5 + 10 · 0.8660


y' = 10.00 + 8.66 = 18.66

Thus, the coordinates (x,y) of point Q after rotation are (12.32, 18.66).

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