Math Problem Statement

Find the exact numerical value of the expression 2sin(π/8)cos(π/8).

Solution

The expression given is:

2sin(π8)cos(π8)2 \sin\left(\frac{\pi}{8}\right) \cos\left(\frac{\pi}{8}\right)

This can be simplified using the double angle identity for sine:

2sin(A)cos(A)=sin(2A)2 \sin(A) \cos(A) = \sin(2A)

So, applying this identity to the given expression with A=π8A = \frac{\pi}{8}:

2sin(π8)cos(π8)=sin(2×π8)=sin(π4)2 \sin\left(\frac{\pi}{8}\right) \cos\left(\frac{\pi}{8}\right) = \sin\left(2 \times \frac{\pi}{8}\right) = \sin\left(\frac{\pi}{4}\right)

The sine of π4\frac{\pi}{4} is a well-known value:

sin(π4)=22\sin\left(\frac{\pi}{4}\right) = \frac{\sqrt{2}}{2}

Thus, the exact numerical value of the expression is:

22\frac{\sqrt{2}}{2}

Would you like further details on the steps?

Here are five related questions for practice:

  1. How would you simplify sin(2A)\sin(2A) if A=π6A = \frac{\pi}{6}?
  2. What is the value of cos(π4)\cos\left(\frac{\pi}{4}\right)?
  3. Can you express sin(π3)\sin\left(\frac{\pi}{3}\right) in terms of simpler radicals?
  4. How would you use the double angle identity to simplify 2sin(π12)cos(π12)2 \sin\left(\frac{\pi}{12}\right) \cos\left(\frac{\pi}{12}\right)?
  5. What are other common trigonometric identities that involve both sine and cosine?

Tip: When simplifying trigonometric expressions, always check for common identities like the double angle or sum-to-product formulas.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Double Angle Identity

Formulas

2sin(A)cos(A) = sin(2A)

Theorems

Double Angle Identity for Sine

Suitable Grade Level

High School - Grades 10-12