a mountain railway AB is of length 864m and rises at an angle of 120° to the horizontal. A train is 856m above sea level when it is at A calculate the height above sea level of the train when it reaches B​

9514 1404 393

  1604 m

Step-by-step explanation:

The relevant trig relation is ...

  Sin = Opposite/Hypotenuse

Here, the "opposite" is the elevation of point B above point A, and the "hypotenuse" is the length of the railway. Then the total height of point B is ...

  B = 856 + 864·sin(120°)

  B = 856 +864(√3)/2 = 856 +432√3 ≈ 1604.246

The height of the train at point B is about 1604 m above sea level.

(0,-3) see attached graph

step-by-step explanation:

a. to solve the system, graph the two equations.

x = y+3 becomes y=x-3 has m=1/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move up 1 unit and 1 unit to the right. plot a point and connect.

y=-4x+3 has m =-4/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move down four units and to the right 1 unit. plot a point and connect.

the solution is the point (x,y) where the two lines intersect. by the graph below it is (0,-3).

b. to solve by substitution, substitute y = -4x-3 into x= y+3

x= (-4x-3) +3

x=-4x

5x=0

x=0

now substitute x = 0 back in to find y.

y= -4(0)-3

y=0-3

y=-3

solution is (0,-3)

c. use elimination by adding the equations together.

x-y=3

4x+y=-3

5x=0

x=0

then substitute into one equation to find y.

y=-4(0)-3

y=-3

i think the answer is b