 trigonometry help please... i have a test tomorrow... help? - XP Math - Forums Sign Up FREE! | Sign In | Classroom Setup | Common Core Alignment  XP Math - Forums trigonometry help please... i have a test tomorrow... help? 07-26-2007 #1 NAZIM Guest   Posts: n/a trigonometry help please... i have a test tomorrow... help? a 6m treee is leaning at an angle of 5* to the vertcal.to prevent the tree from leaning any farther, a support pole neeeds to be placed 2m from the top of the tree, at an angle of 60* with the ground.how long does the pole need to be, to the nearest meter?please show all calculations and the final answer.  07-26-2007 #2 Optimizer Guest   Posts: n/a Draw a triangle ABC, where A= point where pole meets ground, B=point where pole meets tree, C=point where tree meets ground.Angle ACB = 85 deg, since tree is 5 degrees from verticalAngle BAC = 60 degrees, givenAngle ABC = 180 - 85 - 60 = 35 deg, since interior angles of a triangle add up to 180 degSide BC = 6 - 2 = 4m, since pole meets tree 2m from its top.There are several ways to proceed from here; one way is to use the law of sines, wherec / sin(C) = b / sin(B) = a / sin(A)So, c / sin(85) = 4 / sin(60)c = 4 (2/ sqrt(3)) (sin(85) = (8 /sqrt(3)) sin(85)or c = 4.6(Check for math errors above, but the logic should be OK)  07-26-2007 #3 Frank K Guest   Posts: n/a Answer = 4.60 meters or 5 meters to nearest whole meter.Take a triangle ABC with side AB = 4 m,  07-26-2007 #4 DrGerard Guest   Posts: n/a 2 m from the top of the tree is an altitude of about 4 m (more precisely, 3.985 m, which is 4 m multiplied by the cosine of 5 degrees). This altitude is equal to the length of the pole multiplied by the sine of 60 degrees.In other words, the length of the pole is 4 m) cos(5) / sin(60) = 4.6012... mTo the nearest meter, that's 5 m. Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
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