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For tan =4/5 and sin = -4/sqrt41

0 votes

find cos using quotient identities?

asked Oct 26, 2014 in TRIGONOMETRY by anonymous

1 Answer

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Given  tan ø= 4/5 and  sin ø= -4/√ (41)  .

Trigonometric quotient identity  tan ø = (sin ø) / (cos ø) .

 tan ø = (sin ø) / (cos ø)

 tan ø (cos ø) = sin ø 

cos ø = (sin ø) / (tan ø)

Now put tan ø = 4/5 and  sin ø= -4/√ (41)  in the above  equation .

cos ø = (-4/√ (41) ) / ( 4/5)

cos ø = (-4/√ (41)) * ( 5/4)

cos ø = -5/√ (41)

Hence cos ø = -5/√ (41) .

answered Oct 26, 2014 by friend Mentor

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