Between 0^@ and 90^@, the cosine function is a decreasing function. For this let us start from the definition of cosine function. As we know, in a right angled triangle, such as one given below:
![enter image source here]()
cosA=("adjacent side")/("hypotenuse")
To see the performance of the ratio as we increase the angle A, keeping hypotenuse same, we know adjacent side continues to reduce and when A becomes 90^@, adjacent side reduces to 0. This is also seen from its graph too
graph{cos((pix)/180) [-7.03, 153, -0.5, 1.5]}
and we observe that while cos0^@=1, it continues ro reduce and at 90^@, we have cos90^@=0
Hence, cos35^@ < cos45^@ is FALSE. Rather, we have cos35^@ > cos45^@.
