If $a^2 + b^2 = 25, x^2 + y^2 = 17 $ and ax + by = 8, then what is the value of (ay - bx) ?
Answer & explanation
Correct answer: option 4
If $a^2 + b^2 = 25, x^2 + y^2 = 17 $
ax + by = 8,
then what is the value of (ay - bx) = ?
We know that,
(ax + by)2 + (ay - bx)2 = (a2 + b2) × ( x2 + y2)
= 82 + (ay - bx)2 = 25 × 17
= (ay - bx)2 = 425 - 64 = 361
= (ay - bx) = \(\sqrt {361}\) = 19