Given that cos a = -1, we can use the Pythagorean identity sin^2(a) + cos^2(a) = 1 to find sin a.
Since cos a = -1, we have:(-1)^2 + sin^2(a) = 11 + sin^2(a) = 1sin^2(a) = 0sin a = 0
Therefore, sin a = 0.
Given that cos a = -1, we can use the Pythagorean identity sin^2(a) + cos^2(a) = 1 to find sin a.
Since cos a = -1, we have:
(-1)^2 + sin^2(a) = 1
1 + sin^2(a) = 1
sin^2(a) = 0
sin a = 0
Therefore, sin a = 0.