NEED HELP ASAP!! Write the expression as the
sine or cosine of an angle.
sin pi/3 cos pi/7 - sin pi/7 cos pi/3

How to do this , and can some one explain

Find the directions in which the function increases and decreases most rapidly at upper p 0p0. then find the derivatives of the function in these directions. f(x,y)equals=x squared plus xy plus y squaredx2+xy+y2, upper p 0p0left parenthesis 1 comma negative 4 right parenthesis

Which graph of a hyperbola represents the equation 16x^2-y^2=16