## suleka Group Title Is the line through points P(–8, –10) and Q(–5, –12) perpendicular to the line through points R(9, –6) and S(17, –5)? Explain. 2 years ago 2 years ago

1. Hero Group Title

no, because when the lines intersect they should intersect at 90 degree angles. They do not.

2. cinar Group Title

$\tan \theta=\frac{m_1-m_2}{1+m_1m_2}$ $m=\frac{y_2-y_1}{x_2-x_1}$ $m_1=\frac{-5-(-6)}{17-9}=1/8$ $m_2=\frac{-12-(-10)}{-5-(-8)}=-2/3$ $\tan \theta=\frac{-2/3-1/8}{1+(-2/3)*1/8)}=19/22$ $\theta=\tan^{-1} (19/22)$ $\theta=40.8$

3. Hero Group Title

talk about taking it further than necessary

4. cinar Group Title

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5. cinar Group Title

the shortest way is that, if they are perpendicular then multiply of their slop must be -1 if $\theta=90$ then this must $m_1*m_2=-1$ and we know that $m_1*m_2=-1/12$ hence $\theta$ cannot equal to 90