Engineering
Mathematics
Basic Rules of Properties of Triangle
Question

The angles A, B and C of a triangle ABC are in A.P. and a : b = 1 : 3. If c = 4 cm, then the area (in sq. cm) of this triangle is:

43

43

23

23

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Solution

∠B=π3,by sine Rule

sinA=12

⇒A = 30°,a = 2,b=23,  c=4

Δ=12×23×2=23  sq.  cm