Step 1: Determine the coordinates of B.
The coordinates of point B are given from the previous problem.
The coordinates of B are ∗(−2;−2)∗.
Step 2: Determine the equation of BQ.
Q is the midpoint of AC. The coordinates of A are (−7;8) and C are (5;−1).
The midpoint formula is M=(2x1+x2,2y1+y2).
Q=(2−7+5,28+(−1))
Q=(2−2,27)
Q=(−1,27)
Now, find the equation of the line passing through B(−2;−2) and Q(−1;27).
First, calculate the gradient mBQ:
mBQ=x2−x1y2−y1=−1−(−2)27−(−2)=−1+227+24=1211=211
Using the point-slope form y−y1=m(x−x1) with point B(−2;−2):
y−(−2)=211(x−(−2))
y+2=211(x+2)
Multiply by 2 to clear the fraction:
2(y+2)=11(x+2)
2y+4=11x+22
2y=11x+18
The equation of BQ is ∗11x−2y+18=0∗.
Step 3: AM is a median of △ABC. Determine the equation of AM.
M is the midpoint of BC. The coordinates of B are (−2;−2) and C are (5;−1).
M=(2−2+5,2−2+(−1))
M=(23,2−3)
Now, find the equation of the line passing through A(−7;8) and M(23;−23).
First, calculate the gradient mAM:
mAM=x2−x1y2−y1=23−(−7)−23−8=23+214−23−216=217−219=−1719
Using the point-slope form y−y1=m(x−x1) with point A(−7;8):
y−8=−1719(x−(−7))
y−8=−1719(x+7)
Multiply by 17:
17(y−8)=−19(x+7)
17y−136=−19x−133
19x+17y−136+133=0
19x+17y−3=0
The equation of AM is ∗19x+17y−3=0∗.
Step 4: Determine the coordinates of the centroid of △ABC.
The centroid G of a triangle with vertices (xA,yA), (xB,yB), and (xC,yC) is given by the formula:
G=(3xA+xB+xC,3yA+yB+yC)
Using A(−7;8), B(−2;−2), and C(5;−1):
Gx=3−7+(−2)+5=3−9+5=3−4
Gy=38+(−2)+(−1)=38−3=35
The coordinates of the centroid are ∗(−34;35)∗.
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