The solution is:tan(θ) = opp / adj tan(θ) = y/x xtan(θ) = y
Find x:
x = y/tan(θ)
So x = 3/tan(π/6)
Perform implicit differentiation to get the equation:
dx/dt * tan(θ) + x * sec²(θ) * dθ/dt = dy/dt
Since altitude remains the same, dy/dt = 0. Now...
dx/dt * tan(π/6) + 3/tan(π/6) * sec²(π/4) * -π/4 = 0
changing the equation, will give us:
dx/dt = [3/tan(π/6) * sec²(π/6) * π/4} / tan(π/6) ≈ 12.83 km/min