Question

sinA= -3/5 where π<A<3π/2 then the value of cosA/2 is?​

Answer 1

Answer:

8/5

Step-by-step explanation:

sin a =-3/5

squaring on both sides,

sin2a =(-3/5)2

1-cos2a=9/25

- cos2a=9/25-1

- cos2a =9-25/25

-cos2a = -16/25

cos2a=16/25

cos a = √16/25

cos a= 4/5

now,

cos a/2 = 4/5/2

cos a /2 = 4×2/5

cos a/2. = 8/5