How to prove that ##sin (pi/2 – theta)## = ##cos theta## ?
February 20th, 2023
see explanation
using appropriate ##color(blue)” Addition formula ” ##
##• sin(A ± B) = sinAcosB ± cosAsinB ##
hence ## sin(pi/2 -theta) = sin(pi/2) costheta – cos(pi/2)sintheta ##
now ## sin(pi/2) = 1 ” and ” cos(pi/2) = 0 ##
hence ## sin(pi/2)costheta – cos(pi/2)sintheta = costheta – 0 ##
##rArr sin(pi/2 – theta ) = costheta ##
