Quantitative Aptitude – Modern Math – Coordinate Geometry

Slot – 1 – Quantitative Aptitude – Modern Math – Coordinate Geometry – Let T be the triangle formed by the straight line

Q. Let T be the triangle formed by the straight line 3x + 5y – 45 = 0 and the coordinate axes. Let the circumcircle of T have radius of length L, measured in the same unit as the coordinate axes. Then, the integer closest to L is ?

Answer: 9

Solution: given eq of straight line is 3x + 5y – 45 = 0, the line cuts x axis at
Put y = 0, 3x – 45 = 0 or x = 15 , so (15, 0)
Put x = 0, 5y – 45= 0 ,or y = 9
Thus the line cut y –axis at (0,9)

Thus we can say OAB is the triangle T which is right angled triangle so AB will be dia of triangle.
Diameter AB = (9^2 + 15^2)^1/2 = (81+225)^1/2 = (306)^1/2 = 17.54 (approx)
So radius = 17.54/2 = 9 (approx)

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