Question

PLEASE HELP ASAP!!

a coil of wire rotating in a magnetic field induces a voltage e=20sin(πt/4 - π/2). Use an identity to express this in terms of cos πt/4. (Please show your work as well)

Answer 1

Explanation:

e = 20sin(πt/4 - π/2)

= 20[(sinπt/4)(cosπ/2) - (cosπt/4)(sinπ/2)]

Used sin(x - y) = sinxcosy - cosxsiny.

= 20[0 - cosπt/4]

Since cosπ/2 = 0 and sinπ/2 = 1.

= -20cosπt/4.