1-cos2a/1+cosa if 1/3 how much sin²a

(1-cos2A) /(1+cos2A) =tan²A

Proof:

We know that,

cos(A+B) =cosA.cosB-sinA.sinB

=>cos2A=cos(A+A)

=>cos2A=cosA.cosA - sinA.sinA

=>cos2A=cos²A-sin²A

=>cos2A=(cos²A-sin²A)/(cos²A+sin²A

Since {cos²A+sin²A=1}

Divide the numerator & the denominator by (cos²A) to get,

cos2A = {(cos²A-sin²A) ÷cos²A} / {(cos²A+sin²A) ÷cos²A}

cos2A ={(1-tan²A)/(1+tan²A)}

Then,

1-cos2A = 1-[{(1–tan²A)/(1+tan²A)}]

1-cos2A =(1+tan²A-1+tan²A)/(1+tan²A)

1-cos2A=(2tan²A)/(1+tan²A)

And now

1+cos2A=1+[{(1-tan²A)/(1+tan²A)}]

1+cos2A={1+tan²A+1-tan²A}/{1+tan²A}

1+cos2A=2/(1+tan²A)

So now,

(1-cos2A)/(1+cos2A)= {2tan²A/(1+tan²A)}÷{2/(1+tan²A)}

={(2tan²A)(1+tan²A)}÷{2(1+tan²A)}

=tan²A

Step-by-step explanation:

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step-by-step explanation:

region b will make the inequalities y < 2x + 1 and y > -x - 2 true ⇒ answer a

step-by-step explanation:

* lets study the graph and the inequality to solve the question

- the inequality y > -x - 2

∵ the form of the inequality is y > mx + c , m is the slope of the line

  and c is the y-intercept (the line intersect y-axis at point (0 , c)

∴ c = -2 that means the line intersect the y-axis at point (0 , -2)

∵ the sign of the inequality is >

∴ we shad the part over the line

  region a and b

- the inequality y < 2x + 1

∵ the form of the inequality is y > mx + c , m is the slope of the line

  and c is the y-intercept (the line intersect y-axis at point (0 , c)

∴ c = 1 that means the line intersect the y-axis at point (0 , 1)

∵ the sign of the inequality is <

∴ we shad the part under the line

  region b and c

∵ the common region between the two lines is region b

∴ region b will make the inequalities y < 2x + 1 and y > -x - 2 true