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Unformatted text preview: Create assignment, 00224, Homework 9, Apr 08 at 6:09 pm 1 This printout should have 11 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. The due time is Central time. Hinged Mirrors 01 35:04, highSchool, numeric, > 1 min, wording variable. 001 The reflecting surfaces of two intersecting flat mirrors are at an angle of 56 , as shown in the figure. A light ray strikes the horizontal mirror at an angle of 53 with respect to the mirrors surface. 56 53 Figure is not drawn to scale. Calculate the angle . Correct answer: 68 . Explanation: Basic Concept: incident = reflected Solution: 1 2 Figure is to scale. The sum of the angles in a triangle is 180 . In the triangle on the left we have angles , 180  1 2 , and 180  2 2 , so 180 = + 180  1 2 + 180  2 2 , or 1 + 2 = 2 . (1) In the triangle on the right we have angles 1 , 2 , and . 180 = 1 + 2 + , so 1 + 2 = 180  . (2) Combining Eq. 1 and 2, we have = 180  2 = 180  2(56 ) = 68 . As a matter of interest, in the upperhalf of the figure the angles (clockwise) in the triangles from left to right are 37 , 37 , and 106 ; 74 , 34 , and 72 ; 108 , 19 , and 53 ; 127 , 19 , and 34 ; and in the lowerhalf of the figure the angles (counterclockwise) in the triangles from left to right are 19 , 19 , and 142 ; 38 , 34 , and 108 ; 72 , 37 , and 71 ; 109 , 37 , and 34 . keywords: Perpendicular Mirrors 35:04, trigonometry, numeric, > 1 min, nor mal. 002 Consider the case in which light ray A is in cident on mirror 1 , as shown in the figure. The reflected ray is incident on mirror 2 and subsequently reflected as ray B. Let the an gle of incidence (with respect to the normal) Create assignment, 00224, Homework 9, Apr 08 at 6:09 pm 2 on mirror 1 be A = 53 and the point of incidence be located 20 cm from the edge of contact between the two mirrors....
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 Spring '10
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