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  1. ABC is a right angled triangle, right angled at C and p is the length of the perpendicular from C on AB. If a, b and c are the length of the sides BC, CA and AB respectively, then
    1. 1
      =
      1
      -
      1
      p²b²a²
    2. 1
      =
      1
      +
      1
      p²a²b²
    3. 1
      +
      1
      = -
      1
      p²a²b²
    4. 1
      =
      1
      -
      1
      p²a²b²
Correct Option: B

On the basis of question we draw a figure of right angle triangle ABC ,

BC = a, AC = b
∴ AB = √AC² + BC²
AB = √b² + a²

Area of ∆ ABC =
1
× BC × AC
2

Area of ∆ ABC =
1
ab
2

Again,
area of ∆ ABC =
1
× AB × CD
2

area of ∆ ABC =
1
× √a² + b² × p
2

∴
1
ab =
1
√a² + b² × p
22

⇒ ab = √a² + b² × p
On squaring both sides,
a²b² = (a² + b²) p²
⇒
1
=
a² + b²
p²a²b²

⇒
1
=
a²
+
b²
p²a²b²a²b²

⇒
1
=
1
+
1
=
1
+
1
p²b²a²a²b²



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