Find which two sides are perpendicular.
Rotate the triangle about one of those sides.
1. a triangle has vertices at (0,0), (2,1),(1,3). About which line could the triangle be resolved, in order to form one cone?
A) the line at x=2y
B) the line at y=3x
C) the x-axis
D) the y-axis
Could someone please explain how to do this? Thank you.
4 answers
I tested out the theories A and B. None of them worked. So what does is mean by the x-axis and the y-axis? What does that mean?
Should show your work. Let the points (0,0), (2,1),(1,3) be A,B,C
AB has slope 1/2
AC has slope 3
BC has slope -2
So, AB and BC are perpendicular.
So, rotate the triangle about AB or BC
AB is the line y = 1/2 x or x=2y
BC is the line y = -2x+5
So, A is the correct answer.
Check that against your calculations. You might also try actually plotting the points!
AB has slope 1/2
AC has slope 3
BC has slope -2
So, AB and BC are perpendicular.
So, rotate the triangle about AB or BC
AB is the line y = 1/2 x or x=2y
BC is the line y = -2x+5
So, A is the correct answer.
Check that against your calculations. You might also try actually plotting the points!
Oh ok! Thank you
3 answers