Q9 of 54 Page 312

If A, B and C are the angles of a ABC, prove that

Since A, B and C are the angles of a triangle, therefore sum of the angles equals 180°.

∴ A + B + C = 180° ⇒ C + A = 180° - B


Now, consider L.H.S. =


=


=


= cot = R.H.S.


Hence, proved.


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