In aΔ ABC if 3 ∠A = 4∠B = 6∠C, then the value of ∠A =

(a) 60o
(b) 80o
(c) 300
(d) 40o

Anurag Mishra Professor Asked on 10th February 2016 in Maths.
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1 Answer(s)
Best answer

Answer:  (b) 80o

Solution:-
3ÐA = 4ÐB = 6ÐC           (Given)
Then, ÐB = 3/4 ÐA  &  ÐC = 3/6 ÐA => ÐC = ÐA/2        ………………..(1)

As, we know that the sum of all angles of a triangle is 180o.

Then, ÐA + ÐB + ÐC = 180o

From equation (1),
ÐA + 3/4 ÐA + ÐA/2 = 180o
(4 ÐA + 3 ÐA + 2 ÐA)/4 = 180o
9 ÐA = 180 x 4
ÐA = 720/9
ÐA = 90o

Then, the value of ÐA will be 80o.

Hence, the correct answer is option (b) 80o.

Anurag Mishra Professor Answered on 10th February 2016.
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