Answer:
8) AD = 23
9) m<B = 63
10) G(1,-5)
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8)
AD = BC
Thus, x + 21 = 12x - 1
11x = 22
x = 2
So, AD = 23
9)
consecutive angles are supplementary, sum to 180
y/2 + y - 9 = 180
3/2 y = 189
y = 126
so, m<B = 63
10)
Diagonals bisect each other. The midpoint of DF = (-1.5, 0.5)
-1.5 = 2+x/2
x = 1
0.5 = 6+y/2
y = -5
G(1,-5)