Post a New Question

Trig

posted by .

Cos(21)cos(9)-sin(21)sin(9)

  • Trig -

    have you come across this formula ?

    cos(A+B) = cosAcosB - sinAsinB

    your expression matches this

    Cos(21)cos(9)-sin(21)sin(9)
    = cos(21+9)
    = cos30
    = √3/2

Answer This Question

First Name:
School Subject:
Answer:

Related Questions

More Related Questions

Post a New Question