it is really basic question
sin of angle is ratio of opposite side to hypotenuse
cos of angle is ratio of adjacent side to hypotenuse
tan of angle is sin/cos or ratio of opposite side to adjacent side

note your angle is 45, hence non-hypotenuse sides are equal and their ratio returns 1
hence tan 45=1 and 1=100/x implies x=100

romitvsingh wrote:tan 45 degree = x/100

tan 45 degree * 100= x

therefore x= 100 feet , now my question is how do we get the value of x as 100 feet ?