Please do this im lazy asl will give brainliest and a thanks

Express the following as a function of a single angle, cos(60) cos(-20) - sin(60) sin(-20)

What is the explicit formula for this sequence? -7, -4, -1, 2, a.) an = 8 + (b - 1)3 b.) an = -7 + (n - 1)3 c.) an = 3 + (n -1) (-7) d.) an = -7 + (n - )

∆red ≅ ∆ by rule will give brainiest if possible