Q. 225.0( 4 Votes )
If sin α and cos α are the roots of the equation ax2 + bx + c = 0, then b2 =
A. a2 – 2ac
B. a2 + 2ac
C. a2 – ac
D. a2 + ac
Answer :
Equation ax2 + bx + c = 0 has 
and 
as two roots
sin α + cos α = 
sin α × cos α = c/a …eq(1)
…..eq (2)
But sin2 α + cos2 α = 1
∴ a2 (1 + 2 sinα.cos α) = b2
Putting sin α × cos α = c/a, we get,
⇒ b2 = a2 + 2ac.
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