The function
is a parabola concave up, whose solutions are
from here, you can use the quadratic formula
to find that the solutions of the parabola are
So, the parabola is positive if (which wouldn't make sense in our case) or
So, if Tanya caters 25 meals she breaks even, and starting with the 26th meal she will begin to profit.
Answer:
BC ≈ 4.0
Step-by-step explanation:
∠ DCA = 180° - 70° = 110° ( adjacent angles )
∠ DAC = 180° - (30 + 110)° ← sum of angles in triangle
∠ DAC = 180° - 140° = 40°
Using the Sine rule in Δ ACD to find common side AC
=
( cross- multiply )
AC × sin40° = 15 × sin30° ( divide both sides by sin40° )
AC = ≈ 11.668
Using the cosine ratio in right triangle ABC
cos70° = =
=
( multiply both sides by 11.668 )
11.668 × cos70° = BC , then
BC ≈ 4.0 ( to the nearest tenth )