Topic Details (Notes format)

How to Use the Pythagorean Identities in Trigonometry

Subject: Mathematics

Book: Maths Mastery

Key Pythagorean trig identities include sin²(θ) + cos²(θ) = 1, 1 + tan²(θ) = sec²(θ), and 1 + cot²(θ) = csc²(θ). These relationships allow you to convert between trigonometric functions or simplify complicated expressions. For example, if sin(θ) = 3/5, then cos(θ) = √(1 – sin²(θ)) = √(1 – 9/25) = √(16/25) = 4/5. This knowledge extends to verifying trigonometric proofs, analyzing wave functions in physics, or building engineering models that rely on sinusoidal behaviors. Familiarity with Pythagorean identities significantly eases advanced problem-solving in calculus and beyond.

Practice Questions

What is the value of log₃(27)?

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What is the value of x if log(x) + log(4) = log(32)?

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The sum of the squares of two consecutive integers is 145. What are the integers?

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

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A cube has a side length of 4 cm. What is its volume?

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What is the probability of drawing a king from a standard deck of 52 playing cards?

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A sum of money doubles itself in 5 years at simple interest. What is the rate of interest?

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The ratio of two numbers is 3:5, and their sum is 64. What are the numbers?

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

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If the perimeter of a square is 40 cm, what is the area of the square?

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