Two trains, each having a speed of 30 km/h, are headed toward each other on the same straight track. a bird that can fly 60 km/h flies off the front of one train when they are 60 km apart and heads directly for the other train. on reaching the other train it flies directly back to the first train, and so forth. calculate the total distance the bird travels before the trains crash.

Explanation:

Given:

Train's speed

Bird's speed

Distance between the trains  

As the two trains are moving with same velocity they will collide at a distance of 30 km. Let t be the time when they collide

so the bird will be flying with the given velocity for 1 hr before the train collide. Let d be the distance travelled by bird

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explanation:

i think it because equal matrices have equal dimensions, only square matrices can be symmetric. for all indices and . every square diagonal matrix is symmetric, since all off-diagonal elements are zero. in linear algebra, a real symmetric matrix represents a self-adjoint operator over a real inner product space.