Is it possible for x to be negative in the equation arcsin x + arcsin 2x = pi/2?

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In summary, the conversation is discussing the equation sin -1x + sin -12x = ∏/2 and whether x can be a negative value in this equation. The answer is no, as sin-1(x) has the same sign as x and -3∏/2 is not equal to ∏/2. The range of the inverse sine function is also mentioned, as well as some hints to help solve the problem.
  • #1
Michael_Light
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Homework Statement



sin -1x + sin -12x = ∏/2



Homework Equations





The Attempt at a Solution



My question is, is it possible for x to be a negative value? Since ∏/2 is positive. Or I should think that x can be negative because -(3∏)/2 = ∏/2?

Please enlighten me...
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  • #2
sin-1(x) has the same sign as x , so the answer to your question is "No, that's not possible."
 
  • #3
-3pi/2 is not equal to pi/2, but the angle -3pi/2 is equivalent to the angle pi/2.:smile:

The range of the inverse sine function is [-pi/2,pi/2]. -3pi/2 is outside of the range.

Hints to solve the problem:

sin(sin-1(x))=x.

sin(pi/2-α)=cosα.

What is cos(sin-1(x))?

ehild
 

FAQ: Is it possible for x to be negative in the equation arcsin x + arcsin 2x = pi/2?

What is the equation "Arcsin x + arcsin 2x = pi/2"?

The equation "Arcsin x + arcsin 2x = pi/2" is a trigonometric equation that involves the inverse sine function. It states that the sum of the inverse sine of x and the inverse sine of 2x is equal to pi/2 radians or 90 degrees.

What is the domain and range of this equation?

The domain of this equation is all real numbers between -1 and 1, inclusive. This is because the inverse sine function only exists for values between -1 and 1. The range is also between -1 and 1, inclusive, as the sum of two inverse sine functions can never exceed 1 or be less than -1.

What are the solutions to this equation?

There are infinitely many solutions to this equation. Some possible solutions include x = 0 and x = 1/2. Other solutions can be found by using trigonometric identities to manipulate the equation and solve for x.

How can this equation be solved?

This equation can be solved by using algebraic manipulation and trigonometric identities. One method is to use the double angle formula for sine to rewrite the equation in terms of sine only, and then solve for x using the inverse sine function. Another method is to use the Pythagorean identity to convert the equation to a quadratic equation and solve for x.

What is the significance of this equation in mathematics?

This equation is significant because it involves the inverse sine function, which has many real-world applications in fields such as physics, engineering, and statistics. It is also a useful tool for solving trigonometric equations and can help to understand the relationships between different trigonometric functions.

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