Tangents to the curve x2+y2=2 at the points (1, 1) and ( – 1, 1)
x2+y2=2⇒2x+2ydydx =0⇒dydx=−xytherefore , slope of tangent at (1,1) = - 1 and the slope of tangent at ( - 1 ,1 )= 1 .
Now product of the slopes=1.-1= -1
Hence , the two tangents are at right angles.