13.3k views
23 votes
Prove the following identity ​

Prove the following identity ​-example-1

1 Answer

5 votes

Answer:

sec(x)/(tan xsin(x))=cot^2 x+1 = Ture

Explanation:

Verify the following identity:

sec(x)/(tan(x) sin(x)) = cot(x)^2 + 1

Hint: | Eliminate the denominator on the left hand side.

Multiply both sides by sin(x) tan(x):

sec(x) = ^?sin(x) tan(x) (cot(x)^2 + 1)

Hint: | Express both sides in terms of sine and cosine.

Write cotangent as cosine/sine, secant as 1/cosine and tangent as sine/cosine:

1/cos(x) = ^?sin(x)/cos(x) sin(x) ((cos(x)/sin(x))^2 + 1)

Hint: | Simplify the right hand side.

((cos(x)/sin(x))^2 + 1) sin(x) (sin(x)/cos(x)) = (((cos(x)^2)/(sin(x)^2) + 1) sin(x)^2)/(cos(x)):

1/cos(x) = ^?(sin(x)^2 (cos(x)^2/sin(x)^2 + 1))/cos(x)

Hint: | Put the fractions in cos(x)^2/sin(x)^2 + 1 over a common denominator.

Put cos(x)^2/sin(x)^2 + 1 over the common denominator sin(x)^2: cos(x)^2/sin(x)^2 + 1 = (cos(x)^2 + sin(x)^2)/sin(x)^2:

1/cos(x) = ^?sin(x)^2/cos(x) (cos(x)^2 + sin(x)^2)/sin(x)^2

Hint: | Cancel down ((cos(x)^2 + sin(x)^2) sin(x)^2)/(sin(x)^2 cos(x)).

Cancel sin(x)^2 from the numerator and denominator. ((cos(x)^2 + sin(x)^2) sin(x)^2)/(sin(x)^2 cos(x)) = (sin(x)^2 (cos(x)^2 + sin(x)^2))/(sin(x)^2 cos(x)) = (cos(x)^2 + sin(x)^2)/cos(x):

1/cos(x) = ^?(cos(x)^2 + sin(x)^2)/cos(x)

Hint: | Eliminate the denominators on both sides.

Multiply both sides by cos(x):

1 = ^?cos(x)^2 + sin(x)^2

Hint: | Use the Pythagorean identity on cos(x)^2 + sin(x)^2.

Substitute cos(x)^2 + sin(x)^2 = 1:

1 = ^?1

Hint: | Come to a conclusion.

The left hand side and right hand side are identical:

Answer: (identity has been verified)

User Heidi
by
7.7k points

No related questions found

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories