proof left as an exercise

06072022, 05:36 PM
Post: #4




RE: proof left as an exercise
Proof: 2*cos(30°) / (1 + 4*sin(70°)) = tan(20°)
2*cos(30°) / (1 + 4*cos(20°)) ?=? tan(20°) // sin(70°) = cos(20°) 2*cos(30°) ?=? tan(20°) + 4*sin(20°) // cross multiply cos(20°)*cos(30°) ?=? sin(20°)/2 + sin(40°) // multiply by cos(20°)/2 sin(40°) ?=? cos(20°)*cos(30°)  sin(20°)*sin(30°) cos(50°) = cos(20°+30°) // trig angle sum identity Proof is complete, (read it bottomup) 

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Messages In This Thread 
proof left as an exercise  Thomas Klemm  06062022, 11:41 PM
RE: proof left as an exercise  Ángel Martin  06072022, 05:05 AM
RE: proof left as an exercise  Thomas Klemm  06072022, 05:32 AM
RE: proof left as an exercise  Albert Chan  06072022 05:36 PM
RE: proof left as an exercise  Albert Chan  06072022, 06:17 PM
RE: proof left as an exercise  Albert Chan  06082022, 01:50 AM
RE: proof left as an exercise  Albert Chan  06082022, 11:12 AM
RE: proof left as an exercise  Thomas Klemm  06082022, 11:18 PM
RE: proof left as an exercise  Albert Chan  06092022, 12:35 AM
RE: proof left as an exercise  Albert Chan  07012022, 07:51 PM
RE: proof left as an exercise  Albert Chan  07022022, 11:44 PM

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