1.

The points A(1, 5), B(2, 3) and C(-2, -1) are A) vertices of a right-angled triangle B) vertices of an isosceles triangle C) collinear D) non-collinear

Answer»

Correct option is (D) non-collinear

Giver points are A(1, 5), B(2, 3) and C(-2, -1).

\(\therefore\) \(AB=\sqrt{(2-1)^2+(3-5)^2}\)

\(=\sqrt{1+4}\)

\(=\sqrt{5}\) units

\(BC=\sqrt{(-2-2)^2+(-1-3)^2}\)

\(=\sqrt{16+16}\)

\(=4\sqrt{2}\) units

\(AC=\sqrt{(-2-1)^2+(-1-5)^2}\)

\(=\sqrt{9+36}\)

\(=3\sqrt{5}\) units

\(\because\sqrt5<\sqrt{32}<\sqrt{45}\)

\(\Rightarrow AB<BC<AC\)

But AB+BC \(=\sqrt5+4\sqrt2\)

\(=2.236+5.657\)

\(=7.893\neq6.708\)

i.e., AB+BC \(\neq\) AC

\(\therefore\) Points A, B and C are not collinear.

Also, they are not vertices of isosceles & right angled triangle.

Hence, given points A, B and C are non-collinear.

Correct option is D) non-collinear



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