Question

Find the length of the base of the following pyramid given the height of the pyramid is 71 meters and the angle of elevation of the base of the pyramid is 42°.
a. 127 feet

b. 158 feet

c. 191 feet

d. 212 feet

Answer 1

let me see

Answer 2

@johnweldon1993

Answer 3

Well height is 71m...the angle is 42 degrees and you want the length

From that angle..you have height (opposite the angle) and you want length (adjacent to that angle) .

Which trig function uses opposite and adjacent?

Answer 4

sine?

Answer 5

This one will be tangent

\[\large tangent = \frac{opposite}{adjacent}\]

Answer 6

ok

Answer 7

So

\[\tan 42 = \frac{71}{L}\]

You can rearrange this into

\[\large L = \frac{71}{\tan42}\]

Answer 8

okk

Answer 9

now what do i do

Answer 10

Well do that operation first...71 divided by the tangent of 42

Answer 11

i did

Answer 12

And you got?

Answer 13

78.85348855

Answer 14

Right...now as you can see...they ask about the entire length of the base...and the little triangle we just used....looks to be about half that right?

So what do we do now that we want the full base...not just half of it

Answer 15

multiply by 2?

Answer 16

Right...and then round obviously but yeah :)

Answer 17

ok cool. thanks!

Answer 18

No problem!