Find an explicit formula for the arithmetic sequence 12, 5, -2, -9,...12,5,−2,−9,...12, comma, 5, comma, minus, 2, comma, minus,
2 answers:
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Numerator is the the number above the line on a fraction, while the denominator is the number underneath the line.
is similar to 
Fraction with numerator -6 and denominator 8
Fraction with numerator -6 and denominator 8
since its an isoscelies trangle, they probably wanted you to do base times height
make a 71-91/2-x x triangle
where x is the height of the triangle to the base 91 and 71 is the hypothenuse
and then do bh/2
or
use heron's formula
s= 71+91/2
area=
have fun solving that