Which expression represents a number that is one fourth as great as 10-2?

Which sum or difference identity would you use to verify that cos (180° - ∅) = -cos ∅? a. sin (α -β) = sin α cos β – cos α sin β b. cos (α -β) = cos α cos β – sin α sin β c. cos (α -β) = cos α cos β + sin α sin β d. sin (α + β) = sin α cos β + cos α sin β

What two criteria are needed for triangles to be similar

The tile along the edge of a triangular community pool needs to be replaced? ?