Grade 11Trigonometry
in a triangle ABC if B=3C prove that in(A/2) =(b-c)/2c
in a triangle ABC if B=3C prove that in(A/2) =(b-c)/2c
1 Answer
Sudhir Kumar
B = 3C , sin B = sin3C => sinB = sinC(4cos2C – 1)
Using sin law for sinB and sinC => b = c(4cos2 C– 1) => cos2C = (b+c)/4a
A+B+C=180 => A = 180 – 4C =>sin(A/2) = cos2C = 2cos2C – 1 => sin(A/2) = (b – c)/2c
Other Related Questions on trigonometry
In ABC, if cot A+cot B+cot C = cosecA cosecB cosecC, then prove that ABC is right angle triangle.
In ABC, if cot A+cot B+cot C = cosecA cosecB cosecC, then prove that ABC is right angle triangle.
trigonometry
Last Activity: 3 Years ago
- Find the general solution of equation tan3∂=cot2∂
For all angles between -720 and +720
- Find the general solution of equation tan3∂=cot2∂
For all angles between -720 and +720
trigonometry
Last Activity: 4 Years ago
Derive a formula for the area of the triangle, given b, A, B, and C. That is, derive the formula: (b^2sinAsinC)/(2sinB)
Derive a formula for the area of the triangle, given b, A, B, and C. That is, derive the formula: (b^2sinAsinC)/(2sinB)
trigonometry
Last Activity: 4 Years ago
WHAT IS THE LIMIT WHEN X TOWARDS TO 0 OF sin6x/5x ? lim𝑥→0 𝑠𝑖𝑛6𝑥/5𝑥
WHAT IS THE LIMIT WHEN X TOWARDS TO 0 OF sin6x/5x ? lim𝑥→0 𝑠𝑖𝑛6𝑥/5𝑥
trigonometry
Last Activity: 4 Years ago