If the horizontal range of a projectile becomes half of its maximum possible horizontal range, the probable angle of projection is:

  • A. 15 degrees
  • B. 30 degrees
  • C. 45 degrees
  • D. 60 degrees

Explanation

Range is proportional to sin of twice the angle and is greatest at 45 degrees, where sin 90 equals 1, so half the maximum range needs sin 2 theta equal to 0.5, giving 2 theta equal to 30 degrees and theta equal to 15 degrees. The other solution is 75 degrees, since the two angles are complementary. Answering 30 degrees comes from halving the angle instead of the sine.

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