Question

if a=45, verify that (ii) cos2a = 2 cos square A-1=1-2 sin square a​

Answer 1

Answer:

cos90=2cos²45

Step-by-step explanation:

cos 90 is 0 and cos 45 is 1/√2

0= 2(1/√2)²-1

Answer 2

Answer:

cos2(45) ={2cos^2(45) -1)}=1-2sin^2(45)

cos(90) =2[cos(45) ]^2-1=1-2[sin(45) ]^2

0=[2(1/√2) ^2]-1=1-[2(1/√2) ^2]

0=1-1=1-1