How do you simplify cos(t-pi/2)cos(t−π2)?
2 Answers
Aug 8, 2016
sint
Explanation:
We can use the appropriate
color(blue)"addition formula"addition formula
color(red)(|bar(ul(color(white)(a/a)color(black)(cos(A-B)=cosAcosB+sinAsinB)color(white)(a/a)|)))
rArrcos(t-pi/2)=costcos(pi/2)+sintsin(pi/2)
color(orange)"Reminder"
color(red)(|bar(ul(color(white)(a/a)color(black)(cos(pi/2)=0 " and " sin(pi/2)=1)color(white)(a/a)|)))
rArrcostcos(pi/2)+sintsin(pi/2)=0+sint
rArrcos(t-pi/2)=sint This is a useful result and worth memorising for future use.
Sep 21, 2016