Question
Question: If sin a and cosa are roots of the equation px + qx + r = 0, then....
If sin a and cosa are roots of the equation px + qx + r = 0, then.
A
p2 – q2 + 2pr = 0
B
(p + r)2 = q2 – r2
C
p2 + q2 – 2pr = 0
D
(p – r)2 = q2 + r2
Answer
p2 – q2 + 2pr = 0
Explanation
Solution
Here sin a + cos a = –q/p, sin a cos a = r/p
(sin a + cos a)2 = q2/p2
Ž sin2a + cos2a + 2 sin a cos a + q2/p2
Ž 1 + 2r/p = q2/p2 Ž p2 – q2 + 2pr = 0