SinB=1/2 then 3cosB-4cos.cos.cosB
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Answered by
1
Since sinB=1/2, B=30°
substituting B
⇒ 3cos30°- 4COS³30°
⇒3 x √3/2 - 4 x (√3/2)³
⇒3√3/2 -3√3/2
⇒ 0
Answered by
0
sinB=1/2
sin^2B+cos^2B=1
1/4+cos^2B=1
cosB=√3/2
therefore 3cosB-4cos^3B=3√3/2-4x3√3/8
=3√3/2-3√3/2
=0
sin^2B+cos^2B=1
1/4+cos^2B=1
cosB=√3/2
therefore 3cosB-4cos^3B=3√3/2-4x3√3/8
=3√3/2-3√3/2
=0
Punya2138:
This is not correct.
now i realised my mistake
sorry
Its okay. The only way to learn is by making mistakes but make sure you understand and rectify your mistake. All the best.
yeah
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