The sum of the lengths of any two sides of a triangle must be greater than the length of the third side (or else, it can't be a closed polygon). Since we know that the two sides in question are both of the same length in this case (since the triangle isosceles), their individual lengths must be greater than 25/2 = 12.5.
Answer:
13620000
Step-by-step explanation:
Start by combining the fractions:
Recall the Pythagorean identity:
Then cancel a factor of 
and use the definition of secant:
