Suppose sonar on the surface of the sea locates an object at an angle of depression of 65° and a distance
of 320 feet.
How deep is the object?

9514 1404 393

  290 ft

Step-by-step explanation:

The relevant trig relation is ...

  Sin = Opposite/Hypotenuse

  sin(65°) = d/(320 ft)

  d = (320 ft)sin(65°) ≈ 290 ft

The object is about 290 feet deep.

area of part 1:

a1=base*height/2=(8+2)*(8-2-2-1)/2=10*3/2=15 ft^2

area of part 2:

a2=length*width=(8+2)*1=10 ft2

area of part 3:

a3=length*width=8*2=16 ft2

total shaded area : a1+a2+a3=41 ft2

total area of the reactangle : a=16*8=128 ft2

total area of the nonshaded region : 128-41=87 ft2