Question 923934
All you have to do is find the equation
of the line, then find the x and y 
intercepts.
That gives you the legs of a rt. triangle,
so you can find area
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Use the general point-slope formula
{{{ ( y - 1.7 ) / ( x - 5 ) = (  2.2 - 1.7 ) / ( 4 - 5 ) }}}
{{{ ( y - 1.7 ) / ( x - 5 ) = .5 / (-1) }}}
{{{ (-1)*( y - 1.7 ) = .5*( x - 5 ) }}}
{{{ -y + 1.7 = .5x - 2.5 }}}
{{{ y = -.5x + 4.2 }}}
check:
Does it go through ( 4,2.2 )?
{{{ y = -.5x + 4.2 }}}
{{{ 2.2 = -.5*4 + 4.2 }}}
{{{ 2.2 = -2 + 4.2 }}}
{{{ 2.2 = 2.2 }}}
OK- I'll assume the other point is OK
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So, now you have the point ( 0, 4.2 )
and also
( 8.4, 0 ) 
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The area is {{{ (1/2)*b*h }}}
{{{ A = (1/2)*4.2*8.4 }}}
{{{ A = 17.64 }}}
Check my math