Question

The formula for cos a minus b is equals to cos a cos b + sin a sin b find the value of cos 15 degree

Answer 1

Answer:

√3+1/2√2

Step-by-step explanation:

cos (a-b)=cosacosb+sinasinb

15=45-30

cos(45-30)=cos45cos30+sin45sin30

cos15=1/√2×√3/2+1/√2×1/2

cos15=√3/2√2+1/2√2

cos15=√3+1/2√2