Question! (1 Viewer)

[Jono_2007]

How do i approach this question?
The points (0,2), (2,3), (4,0) and (2,-1) are the verticies of a quadrilateral. Find the tangent of the acute angle between its diagonals.

 

[Mountain.Dew]

How do i approach this question?
The points (0,2), (2,3), (4,0) and (2,-1) are the verticies of a quadrilateral. Find the tangent of the acute angle between its diagonals.

okay...u need to find the gradient of the diagonals of the quadrilaterial ur talking about. unlike what vafa posted, there is no need finding the actual equation of the diagonals. just the gradients of those diagonals is sufficient. ( IE m = (y1 - y2) / (x1 - x2) )

once u have m1 and m2 (the gradients m1 and m2), use this formula:

tan@ = | tan(m1 - m2)| , where @ is the acute angle between its diagonals.

nice to know that tan@ IS the tangent of that acute angle ur after.

 

[Jono_2007]

okay...u need to find the gradient of the diagonals of the quadrilaterial ur talking about. unlike what vafa posted, there is no need finding the actual equation of the diagonals. just the gradients of those diagonals is sufficient. ( IE m = (y1 - y2) / (x1 - x2) )

The Equation is m=(y2-y1)/(x2-X1) actually, sorry!

once u have m1 and m2 (the gradients m1 and m2), use this formula:
tan@ = | tan(m1 - m2)| , where @ is the acute angle between its diagonals.
nice to know that tan@ IS the tangent of that acute angle ur after.

Tan @=m1-m2/1+m1.m2 is the formula, but that wasn't the problem. the problem was i was finding the gradients of the wrong combination of points.

 

[Mountain.Dew]

The Equation is m=(y2-y1)/(x2-X1) actually, sorry!

(y2-y1)/(x2-X1) = -[y1-y2]/(-[x1-x2]) = (y1 - y2) / (x1 - x2)

makes no difference at all. as long as u know what values to put in, and at the right places, ur set!

 

[Riviet]

the problem was i was finding the gradients of the wrong combination of points.

It always helps to draw a diagram! Try and make it 85%+ to scale too and determine which two set of points correspond to the diagonals of the quadrilateral.

 

[YBK]

The Equation is m=(y2-y1)/(x2-X1) actually, sorry!

makes no difference, i mean, you're choosing the y1 and y2 anyways.