Answer:
Area of triangle = 15 square units
Step-by-step explanation:
We need to find area of the triangle, given the vertices:
A=(4,0)
B=(1,5)
C=(7,5)
The formula used is: 
We have: 
Putting values and finding area

We will be ignoring negative sign, because area of triangle is positive.
So, Area of triangle = 15
The arc length (s) is given in terms of the radius (r) and central angle (θ) by
s = r*θ . . . . . . . where θ is in radians
For your arc, the length is
s = (15 ft)*(π/4) ≈ 11.78 ft
_____
45° can be converted to radians by multiplying by π/180°.
45° * (π/180°) = π*(45/180) = π/4 . . . . radians
The ODE is linear:


Multiplying both sides by
gives

Notice that the left side can be condensed as the derivative of a product:

Integrating both sides with respect to
yields


Since
,

so that




→ Substitute cos 2x and sin 2x by their expressions

→ Subtract both sides by sin x

→ Take sin x as a common factor in the right side

From the graph, the equation has 4 solutions, the intersection points between the 2 graphs