CosA+SinA=√2CosA then prove that CosA-SinA=√2SinA
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Posted by Yogesh Kumar 5 years, 1 month ago
- 2 answers
Nishihoney Lodha 5 years, 1 month ago
By squaring both sides: (cosA+sinA)2=(√2cosA)2
By adding (cosA +sinA)2 +( cosA -sinA)2----------->cos2A+sin2A+2cosAsinA+cos2A+sin2A-2cosAsinA---------->cos2A+sin2A+cos2A+sin2A------>1+1=2. Now,(cosA-sinA)2=2-(cosA+sinA)2-------->so, (cosA-sinA)2=2-2cos2A------>(cosA-sinA)2=2(1-cos2A)------>(cosA-sinA)2=2sin2A-------->(cosA-sinA)=√2sinA.... Hence,proved. (Here 2 is the power.)
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Paulo Dybala 5 years, 1 month ago
2Thank You