Let y represent the speed of sound, then y = 331+0.6x.
18 degrees means that the speed of sound is 331+10.8 = 341.8 seconds, and the distance is 34 1.8*5= 1709 meters.
2) If ∠AOB is X, ∠BOC is 2x ∠ AOD =1.5x.
∠ BOD =∠ AOD-∠ AOB = 0.5x = 14, then x = 28.
3) Five straight lines intersect, with at most 10 intersection points.
Article 100 has at most 4950 intersections.
N has at most 0.5*n*(n- 1) intersections.
The idea is that the nth straight line must intersect with the nth-1,and at most it is1+2+3+4+...+n- 1.
4) First question, the stop time after two scenic spots is 1 hour.
So it takes two hours to walk, with a speed of 2 kilometers per hour and a distance of 4 kilometers.
The distance of ce is: 4-1-1-1.6 = 0.4 km.
The second question C has two main routes between B and D.
Either follow the route of the first question, walk from point E to point B and then return, that is, A-E-B-E-C-D-A.
Not a-e-b-c-d-a.
The first time is 3+0.5+0.8/2=3.9 hours.
Stay at the second and third scenic spots 1.5 hours.
It takes 5.2/2=2.6 to drive 5.2 kilometers.
The total time is 1.5+2.6=4. 1.
So the first one takes less time.