The distance between the tree and the ground is represent with x
Using pythagoras theorem
[tex]\begin{gathered} 17^2=x^2+4^2 \\ x^2=17^2-4^2 \\ x^2=\text{ 289 - 16} \\ x^2\text{ =273} \\ x\text{ = }\sqrt[]{273}\text{ =16.5 ft} \end{gathered}[/tex]The distance between the tree and the ground is 16.5 feet
In a right angle triangle (i.e a triangle that has one of its angle equal to 90 degrees)
There are three sides, namely; the hypotenus, the opposite and the adjacent
The hypotenus is the side opposite to the right angle, so to identify the hypotenus, locate the 90 degrees, the side facing that right angle is the hypotenus
The opposite side is dependent on the reference acute angle of the other two acute angles while the third side is the adjacent. So with a given reference angle in the triangle, the opposite is the side facing that reference angle.
Pythagoras state that
[tex]\begin{gathered} \text{hyp}^2=opp^2+adj^2 \\ \text{therefore} \\ \text{opp}^2=hyp^2-adj^2 \\ \text{adj}^2=hyp^2-opp^2 \end{gathered}[/tex]In the question hyp = 17 (side facing the 90 degrees), opp = x, adj = 4