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sp asked in Science & MathematicsPhysics · 8 years ago

Consider the laser beam in The figure below, in which L = 4.2 m and H = 2.1 m. At what angle phi should the b?

Consider the laser beam in The figure below, in which L = 4.2 m and H = 2.1 m. At what angle phi should the beam be aimed at the mirrored ceiling in order to hit the midpoint of the far wall?

http://www.webassign.net/knight/p23-9.gif

Please help, I was on a roll and then I got stuck.

1 Answer

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  • Woodsman
    Lv 7
    8 years ago
    Favorite Answer

    Well, angle of incidence = angle of reflection

    If the beam hits x from the left side of the figure, then

    H / x = H/2 / L-x → (L-x)H = Hx/2 → 2(L-x) = x → 2L - 2x = x → 3x = 2L

    x = 2L/3 = 2 * 4.2m / 3 = 2.8 m

    Then Θ = arctan(2.1/2.8) = 37º

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