the complete question in the attached figure
we know that
in the right triangle ABC
Part a)
sin A=opposite side angle A/hypotenuse
opposite side angle A=BC-----> 21
hypotenuse=AB-----> 29
so
sin A=21/29
the answer part a) is
sin A=21/29
part b)
cos A=adjacent side angle A/hypotenuse
adjacent side angle A=AC-----> 20
hypotenuse=AB-----> 29
so
cos A=20/29
the answer part b) is
cos A=20/29
the answer is the option C)
sin A=21/29 and cos A=20/29
