Question

In a triangle ABC A is an obtuse angle, sinA is equal to 4/5 cosB is equal to 12/13 then the value of sinC is

Answer 1

Answer:

since A is obtuse angle ,

If sinA = 4/5 , than cosA = -3/5

tanA = -4/5

Now if A is obtuse rest are acute .

than if cosB = 12/13 , sinB = 5/13

tanB = 5/12

Now we know that A+B+C= 180°

than tanA*tanB*tanC = tanA+tanB+tanC

putting values we get ,

(-4/5)*(5/12)*tanC = -4/5+5/12+tanC

-tanC/3 = -23/60 + tanC

tanC+tanC/3 = 23/60

tanC(4/3) = 23/60

tanC = 23/80

sinC = 23/√5871

( जैसा क्वेश्चन पूछा था वैसा ही answer de diya hai Bhai )

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