The equation of the tangents to the circle x2+y2=a2, which makes a triangle of area a2 sq. units with coordinate axes, is/are
A
x+y=a√2
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
x−y=a√2
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C
2x+3y=2a√3
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
2x−3y=2a√3
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution
The correct options are Ax+y=a√2 Bx−y=a√2 Let the tangent be of form xx1+yy1=1 and area of triangle formed by coordinate axes is: ∣∣∣12x1y1∣∣∣=a2⋯(1) Rearranging equation of tangent, we get xy1+yx1−x1y1=0
Applying condition of tangency ∣∣
∣
∣∣−x1y1√x21+y21∣∣
∣
∣∣=a ⇒x21+y21=x21y21a2
Using equation (1), we get x21+(2a2x1)2=4a2⇒t+4a4t=4a2(t=x21)⇒t2−4a2t+4a4=0⇒t=2a2⇒x21=2a2⇒x1=±a√2⇒y1=±a√2
Hence, the equation of the tangents are x+y=a√2x+y=−a√2x−y=a√2x−y=−a√2