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Brian McLogan
Evaluate the sum of two angles 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...
Brian McLogan
How to determine the function and angle given an expression
👉 Learn all about sum and difference angle identities. In this video playlist, you will learn how to evaluate, solve, simplify and verify using sum and difference angle identities. We will evaluate using angles not found on the unit...
Brian McLogan
Double and Half Angle Formulas | Analytic Trig | Pre-Calculus
In this video we will explore how to use the double angle to evaluate trigonometric expressions from triangles as well as angles in degrees and radians. We will then use double angle formulas to help verify trigonometric identities and...
Brian McLogan
Half angle of cosine given angle in degrees
👉 Learn all about half-angle identities. In this video playlist, you will learn how to evaluate, solve, simplify and verify using half-angle identities. We will evaluate using angles not found on the unit circle as well as sides of a...
Khan Academy
Khan Academy: Trigonometry: Proof: Cos(a+b)=(cos A)(cos B) (Sin A)(sin B)
Video demonstrating the proof for the formula for the cosine of the sum of two angles. Includes link to additional practice problems. [9:22]
Khan Academy
Khan Academy: Trig Identities: Proof: Cos(a+b) = (Cos A)(cos B) (Sin A)(sin B)
Video demonstrating the proof for the formula for the cosine of the sum of two angles.