Exact Value of sin(pi/4)

Questions
1

In a mathinput how do I code the CL to only accept sqrt(2)/2 as an answer for sin(pi/4) instead of a student just typing in sin(pi/4)??

2

You can use a pattern for accepting answers in certain form, or exclusively a particular answer:

p = patterns
genForm = p.fraction(p.radical(p.integer), p.integer)
isRadForm = genForm.matches(this.latex) #or cellContent if in a table
specificAns = p.fraction(p.radical(p.integer.satisfies(`x=2`)), p.integer.satisfies(`x=2`))
isSpecific = specificAns.matches(this.latex)
correct: isSpecific