Question

For triangle XYW, the slope of WX is , the slope of XY is 0.56, and the slope of YW is . Which statement verifies that triangle WXY is a right triangle?

Answer 1

If lines through XY and YW form a 90° angle, so that Y is a right angle, 

then the product of the slopes of the lines through XY and YW must be -1

let the slopes through X,Y and Y,W be $m_X_Y$  and  $m_Y_W$ respectively 

so 

$m_X_Y*m_Y_W=-1$

$m_Y_W= \frac{-1}{m_X_Y}$

$m_Y_W= \frac{-1}{0.56}$

$m_Y_W= -1.786$

Right answer: $m_Y_W= -1.786$