2 Answers

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Let us take a simple example :

Let us consider c= 3,a= 4 and b=5 be the sides of the right angled triangle ABC.

Here a represents the side BC, b represents the side AC and c represents the side AB and the right angled is at B, i.e. <B = 90 degree.

1st Method:

For remaining angle, we use cosine law

i.e. Cos<A =(b*b + c*c - a*a)/(2bc) = ( 5*5 + 3*3 - 4*4) / (2*5*3) = 18/30

i.e. <A = inverse of cos(18/30) = 53 degree (approx)

So, <C = 90 - 53 = 37 degree

2nd Method:

Taking <A as reference angle,

c i.e. AB represents the base

a i.<e. BC represents the perpendicular

and b i.e. AC represents the hypotenuse

Using trigonometric ratio,

tan<A = perpendicular/base = BC/AB =4/3

i.e. <A = inverse of tan(4/3) =53 degree (approx)

So, <C =90 -53 = 37 degree.

Hope you got the solution.

Note: Once practice the given question with given information to understand the given solution.