Proof of inverse trigonometric identities

In summary, the problem asks to prove that the sum of two arcsine values is equal to pi/2. Hint: consider the sine function and use Pythagoras' theorem to find the missing side of a triangle.
  • #1
seboastien
53
0

Homework Statement



Show that arcsin(1/sqrt(5)) + arcsine(2/sqrt(5)) = Pi/2

Homework Equations





The Attempt at a Solution



Can someone please give me so much as a hint?
 
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  • #2
Take the sine of the left-hand side and see if it is equal to sin(pi/2)

ehild
 
  • #3
seboastien said:

Homework Statement



Show that arcsin(1/sqrt(5)) + arcsine(2/sqrt(5)) = Pi/2

Look at each term individually. Each is the arcsine of a ratio, so each term is an angle.

For the first term, if theta = arcsin(1/√5) , then sin(theta) = 1/√5 . Draw a right triangle with one angle being (theta) and having the side opposite (theta) equal to 1 and the hypotenuse equal to √5 . What is the side adjacent to (theta) equal to?

Now, is there an angle in that triangle having a sine of 2/√5 ? If so, it would be an angle which is the arcsine of (2/√5) . Call it (phi) . What do (theta) and (phi) add up to?
 
  • #4
seboastien said:

Homework Statement



Show that arcsin(1/sqrt(5)) + arcsine(2/sqrt(5)) = Pi/2

Homework Equations





The Attempt at a Solution



Can someone please give me so much as a hint?

Draw a triangle and use pythagorus. [Just hints, not answers]
 

Related to Proof of inverse trigonometric identities

1. What are inverse trigonometric identities?

Inverse trigonometric identities are equations that relate the inverse trigonometric functions (arcsine, arccosine, and arctangent) to their corresponding trigonometric functions (sine, cosine, and tangent). These identities allow us to solve for the angle measures of a triangle given the ratio of its side lengths.

2. Why is it important to prove inverse trigonometric identities?

Proving inverse trigonometric identities is important in mathematics and science because it allows us to have a deeper understanding and confidence in the relationships between trigonometric functions. It also helps us to solve more complex problems involving trigonometric functions and their inverses.

3. How do you prove inverse trigonometric identities?

To prove inverse trigonometric identities, we use basic algebraic manipulations and the fundamental trigonometric identities. We also use the definition of inverse trigonometric functions, which state that the inverse of a trigonometric function is equal to the angle whose trigonometric function yields the given ratio.

4. What are some common inverse trigonometric identities?

Some common inverse trigonometric identities include:
- sin(arcsin x) = x
- cos(arccos x) = x
- tan(arctan x) = x
- sin(arccos x) = sqrt(1 - x^2)
- cos(arcsin x) = sqrt(1 - x^2)
- tan(arccos x) = sqrt(x^2 - 1)
- tan(arcsin x) = sqrt(x^2 + 1)

5. How can inverse trigonometric identities be applied in real life?

Inverse trigonometric identities have many applications in real life, such as in navigation, engineering, and physics. For example, inverse trigonometric identities can be used in navigation to calculate the angle of elevation or depression of an object. In engineering, these identities are used to determine the angles and side lengths of triangles in structures. In physics, inverse trigonometric identities are used to analyze the motion of objects in circular or periodic motion.

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