Math Problem Statement

If a = sin^(-1)(√2 / 2) + cos^(-1)(-1 / 2) and b = tan^(-1)(√3) - cot^(-1)(-1 / √3), then find the value of a + b.

Solution

Let's solve this step-by-step.

The problem is:

Given: a=sin1(22)+cos1(12)a = \sin^{-1}\left(\frac{\sqrt{2}}{2}\right) + \cos^{-1}\left(-\frac{1}{2}\right) and b=tan1(3)cot1(13)b = \tan^{-1}(\sqrt{3}) - \cot^{-1}\left(-\frac{1}{\sqrt{3}}\right)

We need to find the value of a+ba + b.

Step 1: Calculate aa

  1. Evaluate sin1(22)\sin^{-1}\left(\frac{\sqrt{2}}{2}\right): sin1(22)=π4\sin^{-1}\left(\frac{\sqrt{2}}{2}\right) = \frac{\pi}{4} because sin(π4)=22\sin\left(\frac{\pi}{4}\right) = \frac{\sqrt{2}}{2}.

  2. Evaluate cos1(12)\cos^{-1}\left(-\frac{1}{2}\right): cos1(12)=2π3\cos^{-1}\left(-\frac{1}{2}\right) = \frac{2\pi}{3} because cos(2π3)=12\cos\left(\frac{2\pi}{3}\right) = -\frac{1}{2}.

Thus, a=π4+2π3a = \frac{\pi}{4} + \frac{2\pi}{3}

To add these, find a common denominator: a=3π12+8π12=11π12a = \frac{3\pi}{12} + \frac{8\pi}{12} = \frac{11\pi}{12}

Step 2: Calculate bb

  1. Evaluate tan1(3)\tan^{-1}(\sqrt{3}): tan1(3)=π3\tan^{-1}(\sqrt{3}) = \frac{\pi}{3} because tan(π3)=3\tan\left(\frac{\pi}{3}\right) = \sqrt{3}.

  2. Evaluate cot1(13)\cot^{-1}\left(-\frac{1}{\sqrt{3}}\right): We know that cot1(x)=tan1(1x)\cot^{-1}(x) = \tan^{-1}\left(\frac{1}{x}\right). So: cot1(13)=tan1(3)\cot^{-1}\left(-\frac{1}{\sqrt{3}}\right) = \tan^{-1}(-\sqrt{3}) and tan1(3)=π3\tan^{-1}(-\sqrt{3}) = -\frac{\pi}{3}

Thus, b=π3(π3)=π3+π3=2π3b = \frac{\pi}{3} - \left(-\frac{\pi}{3}\right) = \frac{\pi}{3} + \frac{\pi}{3} = \frac{2\pi}{3}

Step 3: Calculate a+ba + b

Now we have: a=11π12andb=2π3=8π12a = \frac{11\pi}{12} \quad \text{and} \quad b = \frac{2\pi}{3} = \frac{8\pi}{12}

So, a+b=11π12+8π12=19π12a + b = \frac{11\pi}{12} + \frac{8\pi}{12} = \frac{19\pi}{12}

Final Answer

a+b=19π12a + b = \frac{19\pi}{12}

Would you like further details or have any questions?


  1. What are the properties of inverse trigonometric functions?
  2. How can we simplify expressions involving inverse trigonometric functions?
  3. Why do we convert inverse cotangent to an inverse tangent?
  4. How do we find a common denominator for adding fractions?
  5. Can this solution be verified with approximate numerical values?

Tip: Remember that inverse trigonometric functions have specific ranges, which helps in evaluating them accurately.

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Math Problem Analysis

Mathematical Concepts

Inverse Trigonometric Functions
Addition of Angles
Properties of Trigonometric Functions

Formulas

sin^(-1)(√2 / 2) = π/4
cos^(-1)(-1 / 2) = 2π/3
tan^(-1)(√3) = π/3
cot^(-1)(-1 / √3) = -π/3

Theorems

Range and Properties of Inverse Trigonometric Functions

Suitable Grade Level

Grades 11-12