I would solve this using tangents. Let h be height of flagpole.
Set up 2 right triangles, each with a base of 40.
The larger triangle has height of "h+70"
Smaller triangle has height of 70.
Now write the tangent ratios:
Note: A-B = 9
To solve for h we need to use the "Difference Angle" formula for Tangent
Plug in what we know:
Set up 2 right triangles, each with a base of 40.
The larger triangle has height of "h+70"
Smaller triangle has height of 70.
Now write the tangent ratios:
Note: A-B = 9
To solve for h we need to use the "Difference Angle" formula for Tangent
Plug in what we know: