Question

The value of (Cos 700 Cos 400 + Sin 700

Sin 400

) is​

Answer 1

Answer:

cos 60 = 1/2

Step-by-step explanation:

as we know that,

cosa.cosb - sina.sinb = cos(a-b)

then,

cos700cos400-sin700sin400

= cos (700-400)

= cos300

and cos(360-theta) = costheta

then,

cos 300 = cos(360-300)

= cos60

= 1/2