Topic Details (Notes format)

How to Calculate the Area of Any Triangle Using Trigonometry

Subject: Mathematics

Book: Maths Mastery

For a general triangle with sides a, b and included angle C, the area formula is (1/2)ab sin(C). If you have a=8, b=10, and C=60°, the area is 0.5 × 8 × 10 × sin(60°) = 40 × (√3/2) = 20√3. This approach bypasses perpendicular height by utilizing trigonometric ratios. Applicable in surveying or design, it ensures you can swiftly compute areas without rearranging or dropping altitudes. Mastering this technique broadens your repertoire for geometry problem-solving where direct height measures aren’t readily available.

Practice Questions

A sphere has a radius of 7 cm. What is its volume?

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If a square has a perimeter of 64 cm, what is its area?

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A square is inscribed in a circle with a radius of 5 cm. What is the area of the square?

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If a cone has a radius of 5 cm and a height of 12 cm, what is its slant height?

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If the radius of a circle is 7 cm, what is its circumference?

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If a+b = 10 and ab = 21, what is the value of (a-b)^2?

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

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If the length of a rectangle is doubled and the width is halved, what is the change in area?

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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 x^3 - 3x^2 + 4 = 0, what is one root of the equation?

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