Question

if ABCD is a quadrilateral then cos (A+B/2)+cos(C+D/2)​

Answer 1

Answer:

0

Step-by-step explanation:

A+B = 360 - (C+D) {as ABCD is a rectangle}

cos(a+b/2) + cos(c+d/2)

= cos(360-c-d/2) + cos (c+d/2)

= cos(180 - c+d/2) + cos(c+d/2)

= -cos(c+d/2) + cos(c+d/2) {cos(180-x) = - cos(x)

= 0