Topic Details (Notes format)

How to Use Sum and Difference Identities (Sine, Cosine, Tangent)

Subject: Mathematics

Book: Maths Mastery

Trigonometric sum/difference formulas let you calculate sin(A±B), cos(A±B), tan(A±B) from sin, cos, tan of A and B. For instance, sin(A + B)=sin(A)cos(B)+cos(A)sin(B). A practical scenario: if sin(A) and cos(B) are known, you can find sin(A + B) quickly. These identities fuel transformations, equation solving, and geometry proofs. They also apply to signal processing (phase shifts) and physics (wave interference). Mastering them expands your capacity to handle angles beyond standard reference angles, bridging simpler known values to more complex angle relationships.

Practice Questions

What is the cube of 4?

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A number is increased by 20% and then decreased by 10%. What is the net change?

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If a cone has a base radius of 3 cm and height of 4 cm, what is its slant height?

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How many diagonals does a pentagon have?

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If sin(θ) = 3/5 and θ is an acute angle, what is tan(θ)?

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If a+b = 10 and ab = 21, what is the value of a^3 + b^3?

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What is the greatest common divisor (GCD) of 36 and 48?

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If x + 1/x = 5, what is the value of x^2 + 1/x^2?

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What is the value of log₃(27)?

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The sides of a triangle are 7, 24, and 25. Is this a right triangle?

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