Use an addition or subtraction formula to write the expression as a
trigonometric function of one number:
`\cos \frac(3\pi)(7) \cos \frac(2\pi)(21)
+ \sin \frac(3\pi)(7) \sin \frac(2\pi)(21) =\cos \frac(\pi)(A)
=\frac(B)(2) `.
`A=`
,
`B=`
.
Box 1: Enter your answer as a number (like 5, -3, 2.2172) or as a calculation (like 5/3, 2^3, 5+4)
Enter DNE for Does Not Exist, oo for Infinity
Box 2: Enter your answer as a number (like 5, -3, 2.2172) or as a calculation (like 5/3, 2^3, 5+4)
Enter DNE for Does Not Exist, oo for Infinity