The slope of a line is given by the formula:
![m=(y2-y1)/(x2-x1)](https://img.qammunity.org/2023/formulas/mathematics/high-school/wt3vklmulg2853jxzclws9uvfaplhmpgv7.png)
Where m is the slope, (x1,y1) and (x2,y2) are the coordinates of two points on the line.
In the first line we can identify the next two points: (0,0) and (2,1).
The slope of this line is:
![m=(1-0)/(2-0)=(1)/(2)](https://img.qammunity.org/2023/formulas/mathematics/college/pb0rbrnu2i3aiwm4ls690tc2e635u4rwr4.png)
In the second line, the two points that we can identify are: (0,4) and (2,1).
The slope is then:
![m=(1-4)/(2-0)=(-3)/(2)=-(3)/(2)](https://img.qammunity.org/2023/formulas/mathematics/college/kjt8h7uckpb0g7ci3j5ur39h8t4lhyjnhy.png)
In order to know if they are perpendicular, we need to know that two perpendicular lines have slopes that are negative reciprocal to each other, it means:
![m1\cdot m2=-1](https://img.qammunity.org/2023/formulas/mathematics/college/k61ne1n9beb984omece7ngkfp59s1vu0d9.png)
We need to check if this is true with the two slopes we have, then :
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