Straight Lines

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If we want to find out the the equation of the angle bisector of one of the angles of a triangle, how do we find out which sign(+/-) to take? Sir had told this in class but I can't remember now.

#Mathematics #Co-ordinate Geometry

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Dr.House ·2013-10-15 04:04:05

It depends on whether the angle formed between them is acute or obtuse and signs of the coefficients

Let lines be
ax + by + c = 0 and a'x + b'y + c' = 0

Firstly, write ax + by + c = 0 and a'x + b'y + c' = 0 such that constant terms are positive.

If aa' + bb' > 0, then the equation of the acute angle bisector is with + sign and obtuse is with - sign

If aa' + bb' < 0, then the equation of the acute angle bisector is with - sign and obtuse is with + sign

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Anurag Ghosh ·2013-10-15 05:52:11

There was sumthing sort of this also....by making the signs of the constants of the 2 straight lines equal and then taking the + sign in the equation.....
ax+by+c/(âˆša^2+b^2) = a'x+b'y+c'/(âˆša'^2+b'^2)

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∫ ∫ ∫ ∫ ∫ ∬ ∬ ∬ ∬ ∬ ∭ ∭ ∭ ∭ ∭ ⨌ ⨌ ⨌ ⨌ ⨌

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° ∂ ∞ α β γ δ θ λ μ ν ξ π ρ σ φ ω ε ƒ κ τ υ Γ Δ Λ Σ Π Ω

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Straight Lines

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