A triangular prism has 6 vertices. :)
Not sure however I keep getting 1
Multiply the numerator and denominator by 7×2 = 14 to eliminate the denominators of those fractions:

Rationalize the denominator by multiplying both numerator and denominator by √10:

Lastly, cancel the common factor of 2 in both the numerator and denominator (which comes from 6 = 2×3 and 490 = 2×245):
