DIFFERENTIATION

1-x2 + √1-y2=a(x-y)

Then Prove that dy/dx=√1-y2/1-x2

6 Answers

1
MATRIX ·

No replies!!!!!!!!!!!

62
Lokesh Verma ·

this i think is from A Das Gupta..

-x/√1-x2 - y/√1-y2 (dy/dx) = a(1-dy/dx)

-x/√1-x2 - y/√1-y2 (dy/dx) = (√1-x2 + √1-y2)(1-dy/dx) / (x-y)

(√1-x2 + √1-y2) / (x-y) + x/√1-x2 = - y/√1-y2 (dy/dx) + (√1-x2 + √1-y2)(dy/dx) / (x-y)

(1-x2 + √1-y21-x2 + (x-y)x )/√1-x2 = (- y(x-y) + (√1-x21-y2 + 1-y2)(dy/dx) /√1-y2

(1-x2 + √1-y21-x2 + (x-y)x )/√1-x2 = (- y(x-y) + (√1-x21-y2 + 1-y2)(dy/dx) /√1-y2

(1-yx + √1-y21-x2 )/√1-x2 = ( -yx + 1 + (√1-x21-y2 ) dy/dx) /√1-y2

Thus,

dy/dx=√1-y2/√1-x2

1
MATRIX ·

bhaiyya my sir gave as homework which when solved not getting..........

1
MATRIX ·

but bhaiyya cant we do with x=sinθ

62
Lokesh Verma ·

I thought that first.. then i realised that this was possible like this too :)

1
MATRIX ·

let x=sinθ and x=sinφ
θ=sin-1x and φ=sin-1y

substituing..........

u'll get
1-sin2θ+√1-sin2φ=a(sinθ-sinφ)

so
cos2θ + √cos2φ=a(sinθ-sinφ)

a=(cosθ+cosφ)/(sinθ-sinφ)

applying properties.........

a= (2 cos (θ+φ)/2 cos(θ-φ)/2) / (2 cos (θ+φ)/2 sin(θ-φ)/2)

= cos (θ+φ)/2 sin(θ-φ)/2

= cot(θ+φ)/2

2cot-1a=θ+φ

sinx+siny=2cot-1a

Differentiating..........

1/√1-x2 -1/√1-y2 dy/dx= 0

1/√1-x2 =1/√1-y2 dy/dx

Thus.............

dy/dx=1/√1-x2/1/√1-y2

dy/dx=√1-y2/√1-x2

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