Area of ABC : AB*AC/2
the maximum of the parabola is reached at x=-4/(2*(-1))=2 hence A is at (2,0) and B is at (2,(-2)^2+4*2+C)=(2,12+C)
C is the second root (x-intersect), which we can find :
determinant1 : D=16-4*(-1)*C=4(4+C) thus the second root is at x=

Hence the area of the triangle is

hence

.
We remark that

Hence 4+C=16 thus
C=12
Step-by-step explanation:
step 1. so ABC is a triangle.
step 2. interior angles of a triangle add up to 180°
step 3. <A + <B + <C = 180°
step 4. 54 + <B + 74 = 180°
step 5. <B = 52°.
Answer:
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