What is the value of cos(45-beta)

Step-by-step explanation:

cos (x-y)=cos x cos y+sin x sin y

cos(45-β)=cos~45~cos~β+sin~45~sin~β

ca = ec

cpctc makes it so that corresponding parts of the triangle you proved to be equal are equal, the other options aren't part of the part of the triangles you proved to be equal.