Write the Product as a Sum $\cos 7 x \cos 3 x$

question 97

Multiple Choice

Write the product as a sum. $\cos 7 x \cos 3 x$

• A) \(\cos 7 x + \cos 3 x\)
• B) \([ \cos 7 x + \cos 3 x ] / 2\)
• C) \([ \cos 10 x + \cos 4 x ] / 2\)
• D) \(- [ \cos 5 x + \cos 2 x ] / 2\)
• E) none of these

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Definitions:

National Income

Total income earned by resource suppliers for their contributions to gross domestic product plus taxes on production and imports; the sum of wages and salaries, rent, interest, profit, proprietors’ income, and such taxes.

Developing Countries

Nations with a lower level of industrialization, lower living standards, and lower Human Development Index (HDI) than developed countries.

Per Capita Income

This is the average income earned per person in a given area in a specified year.

Developing Nations

Countries that are in the process of industrialization and have lower per capita income levels compared to developed countries.