Question

Find k, if R (1, -1), S (-2, k) and slope of line RS is -2.

Answer 1

R(x₁ , y₁ ) = R (1, -1), S (x₂ , y₂ ) = S (-2, k) 

Here, x₁ = 1, x₂ = -2, y₁ = -1, y₂ = k

Slope of lines RS = (y₂ - y₁)/(x₂ - x₁) 

= (k - (-1))/(-2 - 1) = (k + 1)/-3

But, slope of line RS is -2. … [Given] 

∴ -2 = (k + 1)/-3

∴ k + 1 = 6 

∴ k = 6 – 1 

∴ k = 5