If A is a 5 x 2 matrix and the product AB is 5 x 7, what is the size of B? X

I. Use De Moivre's Theorem to solve the following. 1. Use de Moivre's theorem to express sin50 in terms of powers of sin0. 2. By considering the solutions of sin50 = 0, find an exact representation for sin? ("). II. Use Cauchy – Reimann Equations to identify if it is differentiable or not, if yes then differentiate the complex equation. 1. f(z) = y – 2xy +j(-x² + x² – y²) + x² – y² + 2jxy 2. f(z) = cosx – jsinhy

Please help.  Need to find BC. (multiplying matrices b and c)

1. Determine the size of the matrix, if not possible, state why. Pay attention to multiplication verses addition when looking for the size! A4X2 – 3B4X2 a. b. A4x2 B2X12 C. B10x3 A10x3