Question

If sec A=5/4
prove
that cos2 A = 1 - sin? A.​

Answer 1

Answer:

now Mark me as brainliest

Answer 2

Answer:

Step-by-step explanation:

Hey mate here is your answer:

Given : Sec A=5/4 = Hypotenuse/adjacent side,

So,Hypotenuse=5,

Adjacent side=4,

Opposite side² = 5²-4²(according to pythagoras theorem),

Opposite side²=25-16,

Opposite side²=9,

So,opposite side = √9 = 3.

Now,prove that Cos 2 A=1-sin? A,

Cos=Adjacent side/Hypotenuse,

Sin=opposite side/Hypotenuse,

Substitute the values given:

2(4/5)=1/1-(3/5)?,

8/5=(2/5)?

8=(2)?,

So,?=8/2=4,

Now substitute the values:

8/5=(2/5)4,

8/5=8/5.

Hope it helps you and please do mark me as Brainliest.