We use trigonometry because we know an angle and a side length.
We are looking for one of the sides that isn't the hypotenuse:
As illustrated by the picture I made below:
We know both unknown angles will be 45 degrees, as there are 180 degrees in a triangle, we know the triangle is a right angle triangle (has 90 degrees) so, (180-90)/2 = 45
Using SOH CAH TOA, short for : SIN- OH COS- AH TAN- OA
We are looking for the one with H, as we know what H is.
I am picking "SIN- OH", but we could use "COS- AH"
The formula for this is: Sin(angle) = O/H
We substitute the angle (45) and the length for H (16)
Sin(45)= O/16 <- rearrange it
Sin(45)*16= O <- Solve in the calculator
13.6145 (4 DP)= O
The legs = O
The legs have a length of "13.6145 (4 DP)" each
