Explanation:
as this is a right-angled triangle, we use Pythagoras to get also c :
c² = a² + b² = 2² + 7² = 4 + 49 = 53
c = sqrt(53)
we know, sine = opposite/Hypotenuse.
so,
sin(A) = 2/sqrt(53) = 0.274721128...
from the norm circle we know cosine is the other leg of the right-angled triangle :
cos(A) = 7/sqrt(53) = 0.961523948...
tan(A) = sin(A)/cos(A) = 2/7 = 0.285714286...
sec(A) = 1/cos(A) = sqrt(53)/7 = 1.040015698...
csc(A) = 1/sin(A) = sqrt(53)/2 = 3.640054945...
cot(A) = 1/tan(A) = cos(A)/sin(A) = 7/2 = 3.50
oh, and FYI :
A = 15.9453959...°