1.

Verify the following: (0, 7, -10), (1, 6, -6) and (4, 9, -6) are vertices of an isosceles triangle.

Answer»

Given: Points are A(0, 7, -10), B(1, 6, -6) and C(4, 9, -6) 

To prove: the triangle formed by given points is an isosceles triangle Isosceles right-angled triangle is a triangle whose two sides are equal 

Formula used: The distance between any two points (a, b, c) and (m, n, o) is given by,

  \(\sqrt{(a−m)^2+(b−n)^2+(c−o)^2}\)

Therefore, 

Distance between A(0, 7, -10) and B(1, 6, -6) is AB,

\(\sqrt{(0-1)^2+(7-6)^2+(-10-(-6))^2}\) 

\(\sqrt{(-1)^2+1^2+(-4)^2}\) 

\(\sqrt{1+1+16}\) 

\(\sqrt{18}\) 

\(3\sqrt{2}\) 

Distance between B(1, 6, -6) and C(4, 9, -6)is BC,

\(\sqrt{(1-4)^2+(6-9)^2+(-6-(-6))^2}\) 

\(\sqrt{(-3)^2+(-3)^2+0^2}\) 

\(\sqrt{9+9}\) 

\(\sqrt{18}\) 

\(3\sqrt{2}\) 

Distance between A(0, 7, -10) and C(4, 9, -6) is AC,

\(\sqrt{(0-4)^2+(7-9)^2+(-10-(-6))^2}\) 

\(\sqrt{(-4)^2+(-2)^2+(-4)^2}\) 

\(\sqrt{16+4+16}\) 

\(\sqrt{36}\) 

= 6

Clearly, 

AB = BC 

Thus, Δ ABC is an isosceles triangle 

Hence Proved



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