Cos(a+b)cosb+ sin(a+b)sinb= cosa

To describe a sequence of transformations that maps triangle abc onto triangle a"b"c", a student starts with a reflection over the x-axis. how should the student complete the sequence of transformations to map triangle abc onto triangle a"b"c"? plz

Give all possible names for the line shown. calculation tip: lines can be written with either point first.

In the following diagram it is given that dec, ab || dc, ad || eb, and ad is congruent to bc. a)why isn't abc a parallelogram even though it has a pair of parallel sides and a pair of congruent sides b)explain why be must be congruent to bc. further explain what type of triangle this makes triangle abc and what it tells you about angle 1 and angle 2c) finally why must angle 3 be congruent to angle 1? further, explain why we know that angle 3 is congruent to angle 2