Ask Question
5 January, 05:22

What is the proof the formula for cos (A+B) = cosAcosB-sinAsinB?

+2
Answers (1)
  1. 5 January, 05:50
    0
    Given data, cos (A - B) = cosAcosB + sinAsinB

    let, A=60' and B=30' (here the ' sign bears degree)

    L. H. S = cos (A - B)

    =cos (60'-30) (using value of A and B)

    =cos30'

    = sqrt3/2

    R. H. S = cosAcosB + sinAsinB

    =cos60' cos30' + sin60' sin30'

    = 1/2 * sqrt3/2 + sqrt3/2*1/2

    = sqrt3/4 + sqrt3/4

    =2 sqrt3/4

    = sqrt3/2

    so L. H. S = R. H. S or cos (A - B) = cosAcosB + sinAsinB
Know the Answer?
Not Sure About the Answer?
Find an answer to your question 👍 “What is the proof the formula for cos (A+B) = cosAcosB-sinAsinB? ...” in 📗 Mathematics if the answers seem to be not correct or there’s no answer. Try a smart search to find answers to similar questions.
Search for Other Answers