Question

A=B=60° then verify: Cos(A -B) = CosA CosB + SinA SinB​

Answer 1

Answer:

given A=B=60

verification

cos (A-B) = cosA cosB + sinA sinB

cos(0 -0 ) = cos60 cos60 + sin60 sin60

$cos( {0}^{0} - {0}^{0}) = \frac{1}{2} \times \frac{1}{2} + \frac{ \sqrt{3} }{2} \times \frac{ \sqrt{3} }{2}$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{1}{4} + \frac{3}{4}$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{1 + 3}{4} = \frac{4}{4}$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: {cos0}^{0} = 1$

Answer 2

Answer:

$1$

Step-by-step explanation:

It is the correct answer.