Three arithmetic means between 3 and negative 13

- 9, - 5, - 1

Step-by-step explanation:

Calculate the mean of 3 and - 13, that is

= = - 5

That is

- 13, - 5, 3

Now find the mean of - 13 and - 5, and - 5 and 3

= = - 9

= = - 1

Thus

- 13, - 9, - 5, - 1, 3

2.2°  

step-by-step explanation:

let θ = the angle of elevation.

tanθ =77/2020

tanθ = 0.038 12

      θ = tan⁻¹0.038 12

      θ = 2.2°