A man wants to cut down a tree in his yard. To ensure that the tree doesn't hit anything, he needs to know the height of the tree. He
measures his distance from the tree at 15 meters and the angle of
elevation to the tree at 86 degrees. What is the height of the tree to the
nearest tenth of a meter?

the answer is -6

step-by-step explanation:

the answer is -6 because its next to the variable m

x^2 + 81

we can factor this using difference of square binomials.

rewrite the equation:

x^2 - (-81)

factor:

(a^2 - b^2) = (√a^2 + √b^2)(√a^2 - √b^2)

(x^2 - (-81) = (x + √-81)(x - √-81)

we can remove the - from under the radical by multiplying it by i.

(x^2 - (-81) = (x + i√81)(x - i√81)

(x^2 - (-81) = (x + 9i)(x - 9i)

we can check our answer by using foil:

x^2 - 9ix + 9ix - 81i^2

x^2 - 81^2

i^2 = -1

x^2 + 81

the easiest way to do these would be to solve the equations. if you can solve the equation than you can solve these problems.