Using sum and difference formula to find the exact value with cosine

👉 Learn how to evaluate the cosine of an angle in radians using the sum/difference formulas. To do this, we first express the given angle as a sum or a difference of two (easy to evaluate) angles, then we use the unit circle and the Pythagoras theorem to identify the angles and obtain all the needed trigonometric function values of the angles. When we know the trigonometric function values of the two angles to be added or subtracted, we can apply the sum and difference formulas to evaluate the cosine of the given angle.

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Organized Videos:
✅ Sum and Difference Formulas
   • Sum and Difference Formulas  
✅ Evaluate Sum and Difference Formulas from a Triangle
   • Evaluate Sum and Difference Formulas ...  
✅ Simplify an Expression using Sum and Difference Formulas
   • Simplify an Expression using Sum and ...  
✅ Write the Expression as a single function | Sum and Difference Formulas
   • Write the Expression as a single func...  
✅ Verify Identities using Sum and Difference Identities
   • Verify Identities using Sum and Diffe...  
✅ Evaluate Tangent using Sum and Difference Formulas
   • Evaluate Tangent using Sum and Differ...  
✅ Evaluate Cosine using Sum and Difference Formulas
   • Evaluate Cosine using Sum and Differe...  
✅ Evaluate Sine using Sum and Difference of Two Angles
   • Evaluate Sine using Sum and Differenc...  
✅ Solve Equations using Sum and Difference Formulas
   • Solve Equations using Sum and Differe...  

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