If sin23=a,express cos 113 in terms of a.
To express cos 113 in terms of a, we can use the trigonometric identity:
cos(x) = sin(90 - x)
In this case, x = 113. So cos 113 can be expressed as:
cos 113 = sin(90 - 113)
To find the value of sin(90 - 113), we need to determine the value of (90 - 113).
90 degrees is a right angle, so 90 - 113 = -23 degrees. Therefore, we need to find sin(-23).
To express sin(-23) in terms of a, we can use another trigonometric identity:
sin(-x) = -sin(x)
So, sin(-23) = -sin(23) = -a.
Therefore, cos 113 = sin(90 - 113) = sin(-23) = -a.