A person starts from his home moves 15 m towards east and then turn 45...
° to his left and walks 10 m. He then turns 135° to his right and walks 5 m. Finally, he turns 180° to his left and walks 20 m. Where is he now with respect to his starting point?
To solve this problem, we need to use vector addition. We can represent each of the four movements as vectors, where the magnitude of the vector is the distance covered and the direction of the vector is the direction of the movement.
Let's call the starting point O. The first movement towards east can be represented as a vector OA of magnitude 15 m and direction east. The second movement turning 45° to the left can be represented as a vector AB of magnitude 10 m and direction north-east. The third movement turning 135° to the right can be represented as a vector BC of magnitude 5 m and direction south-east. The fourth movement turning 180° to the left can be represented as a vector CD of magnitude 20 m and direction south.
We can add these vectors using the parallelogram law of vector addition. Drawing a diagram, we can see that the vectors AB and BC form a right angle, and similarly the vectors CD and BC form a right angle. So we can add these vectors in two steps: first add OA and AB to get the vector AC, and then add BC and CD to get the vector BD. The final position of the person is the endpoint of BD, which we can call point P.
To add OA and AB, we can use trigonometry to find the components of AB in the east and north directions. Since AB forms a 45° angle with the east direction, it has the same magnitude in both directions. So the component of AB in the east direction is 10 m / sqrt(2), and the component in the north direction is also 10 m / sqrt(2). Therefore, the vector AC has a magnitude of sqrt((15 + 10/sqrt(2))^2 + (10/sqrt(2))^2) = 24.14 m, and forms an angle of atan(10/sqrt(2) / (15 + 10/sqrt(2))) = 30.96° with the east direction.
To add BC and CD, we can use the fact that they form a straight line. So the vector BD has a magnitude of 5 + 20 = 25 m, and forms an angle of 180° - atan(10/sqrt(2) / (15 + 10/sqrt(2))) = 149.04° with the east direction.
Therefore, the final position P is 24.14 m east and 25 m south of the starting point O. We can use the Pythagorean theorem to find the distance between O and P: sqrt((24.14)^2 + (25)^2) = 34.18 m. So the person is 34.18 m away from his starting point, in a south-east direction.