Question

If sin A = 0.4, find cos 2A using multiple angle formula.​

Answer 1

Answer:

0.68

Step-by-step explanation:

The suitable multiple angle identity is

2sin²A=1-cos(2A)_______i

Now,

sin²A=(0.4)²=0.16

So,

keeping this value in equation i,

we get

2×0.16=1-cos2A

0.32=1-cos2A

cos2A=1-0.32

cos2A=0.68

Hope this is helpful

Thanks !!

Answer 2

Given,

Sin A = 0.4

To find,

cos 2A

Solution,

We can simply solve the above question by using the formula of cos 2A.

cos 2A = 1-2sin²A

            = 1-2(0.4*0.4)

            = 1-2(0.16)

            =  1-0.32

            =0.68

Hence,  the value of cos 2A using the multiple angle formula is 0.68.