using fundamental identities

[alyren]

use fundamental identities and/or the complementary angle theorem to find the exact value of the expression. do not use a calculator.

cos40sin50 + sin40cos50 ( note: i know there is degree after each numbers)

so far i got

sin(90-40)sin50 + cos(90-40)cos50
= sin50sin50 + cos50cos50
=(sin^2) 50degree + (cos^2) 50degree
=1

is this right?

 

[mmm4444bot]

Looks okay.

Sine and cosine are functions, so we can also use function notation.

sin(50 degrees)^2 + cos(50 degrees)^2 = 1