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Grade 12Differential Calculus

cos inverse(x^2/2 + square root of 1-x^2 * square root of 1- x^2/4)=cos inverse x/2 - cos inverse x holds for what value of x?

Profile image of SHIVAM JAIN
15 Years agoGrade 12
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1 Answer

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ApprovedApproved Tutor Answer1 Year ago

To solve the equation involving the cosine inverse function, we need to analyze the expression carefully. The equation is:

cos-1(x2/2 + √(1 - x2) * √(1 - x2/4)) = cos-1(x/2) - cos-1(x).

First, let's simplify the left-hand side of the equation. The term inside the cosine inverse function can be rewritten. We know that:

  • √(1 - x2) represents the sine of an angle when x is the cosine of that angle.
  • √(1 - x2/4) can also be interpreted similarly.

Now, let's denote:

  • y = cos-1(x)
  • Then, cos(y) = x.

Using this substitution, we can express the left-hand side as:

cos-1(x2/2 + √(1 - x2) * √(1 - x2/4)) = cos-1(x2/2 + (√(1 - x2) * √(1 - (x2/4)))

Next, we can simplify the term inside the cosine inverse. Let's calculate:

√(1 - x2/4) = √(4 - x2) / 2.

Now, substituting this back, we have:

cos-1(x2/2 + (√(1 - x2) * (√(4 - x2

Next, we can analyze the right-hand side:

cos-1(x/2) - cos-1(x) can be rewritten using the cosine subtraction formula:

cos-1(x/2) - cos-1(x) = cos-1(x/2 * x) = cos-1(x2/2).

Now, we can equate both sides:

cos-1(x2/2 + (√(1 - x2) * (√(4 - x2-1(x2/2).

For the equality to hold, the arguments of the cosine inverse must be equal:

x2/2 + (√(1 - x2) * (√(4 - x22/2.

Subtracting x2/2 from both sides gives us:

√(1 - x2) * (√(4 - x2

This implies that either √(1 - x2) = 0 or √(4 - x2

Solving these gives us:

  • From √(1 - x2) = 0, we find x = ±1.
  • From √(4 - x2

However, since x must lie within the range of the cosine function, which is [-1, 1], the only valid solution is:

x = 1.

Thus, the equation holds true for x = 1.