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 April 16th, 2018, 10:19 AM #1 Newbie   Joined: Apr 2018 From: East London Posts: 12 Thanks: 0 Trig double angles Sin (x+60) = 2 Sinx Solve for x Last edited by Vee88; April 16th, 2018 at 10:30 AM. April 16th, 2018, 10:47 AM #2 Global Moderator   Joined: Dec 2006 Posts: 20,636 Thanks: 2080 sin(x)cos(60°) + cos(x)sin(60°) = 2sin(x) tan(x)/2 + √3/2 = 2tan(x) sqrt(3) = 3tan(x) tan(x) = 1/√3 x = (30 + 180k)°, where k is an integer. April 16th, 2018, 10:56 AM #3 Newbie   Joined: Apr 2018 From: East London Posts: 12 Thanks: 0 General Solution Trig Determine the General Solution 4Cos^2 (-x) - Sin (2x -180)= Tan^2 675 April 16th, 2018, 10:56 AM #4 Newbie   Joined: Apr 2018 From: East London Posts: 12 Thanks: 0 Thank you for the above Skip April 16th, 2018, 11:46 AM #5 Global Moderator   Joined: Dec 2006 Posts: 20,636 Thanks: 2080 4cos²(-x) - sin(2x - 180°)= tan²(675$^\circ$) 4cos²(x) + sin(2x) = 1 4cos²(x) + 2sin(x)cos(x) = cos²(x) + sin²(x) sin²(x) - 2sin(x)cos(x) + cos²(x) = 4cos²(x) (sin(x) - cos(x))² = (2cos(x))² sin(x) - cos(x) = ±2cos(x) sin(x) = cos(x) ± 2cos(x) = -cos(x) or 3cos(x) tan(x) = -1 or 3 x = (135 + 180k)$^\circ$ or arctan(3) + 180k$^\circ$ where (by use of a calculator) arctan(3) = 71.565051177...$^\circ$ and k is an integer. Tags angles, double, trig Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post Alavanca11 Trigonometry 2 February 23rd, 2017 01:23 PM MCity98 Trigonometry 1 September 16th, 2013 05:51 PM dunn Trigonometry 4 October 2nd, 2011 10:37 AM farmtalk Trigonometry 6 May 12th, 2011 07:57 PM advancedfunctions Algebra 4 April 14th, 2010 04:22 PM

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