Given the arithmetic sequence 9, 19, 29, 39... find a(n)

first of look for their common difference which is subtract first term from second term 19_9=10

Then use the formula.

a+(n_1)d

9+(5_1)10

9+(4)10

9+40

n=49

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°