If R is the circum radius of `DeltaABC`, then A `(DeltaABC)`= . . .

Options

A. `(abc)/(R)`
B. `(abc)/(4R)`
C. `(abc)/(R)`
D. `(abc)/(2R)`

Answer

B

Explanation

In any `DeltaABC` we know that
Area of `Delta = (1)/(2)` bc sin A
`rArr " "sin A = (2Delta)/(bc)" "…….(i)`
also `" "R=(a)/(2 sin A)" "……(ii)`
From Eqs. (i) and (ii) , we have
`R =(a)/(2((2Delta)/(bc)))`
`rArr " "Delta = A(DeltaABC) =(abc)/(4R)`