# Worksheet: Product-to-Sum Identities

In this worksheet, we will practice using the product-to-sum identity to simplify and evaluating trigonometric expression.

**Q4: **

Write the expression as a sum or difference of trigonometric expressions.

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**Q5: **

Find the exact value of .

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**Q6: **

Write the expression as a product of trigonometric expressions.

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**Q7: **

Find the value of given .

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**Q8: **

Find given and where and are acute angles.

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**Q9: **

The intensity of an electric current is given by where is the time in seconds. Find the intensity after one second without using a calculator using sum and product formulae.

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**Q10: **

Find the value of .

**Q11: **

Find the value of .