I need help with this please

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

In order to be invited to tutoring or extension activities a students performance 20 point higher or lower than average for the

Two corresponding sides of two similar triangles are 3cm and 5cm. the area of the first triangle is 12cm2. what is the area of the second triangle?