Does 1 - (tan 25 degs)(tan 110 degs) equal 1? If so, how?

2 answers

of course not.

If 1-u = 1, then u=0. Unless one of those tan values is zero, the assertion is false.
The tangent of 25 degrees is in quadrant I, this means that the tangent is going to have a positive value. The tangent of 110 degrees is in quadrant II and will have a negative value. If you multiply a negative by a positive, the end product is a negative.

1- (said negative #) =
1+(the number)=
Therefore the sides are not equal.

Verdict: False; cannot be equal to 1.