Q1
sin θ is defined as:
Aopposite/hypotenuse
Badjacent/hypotenuse
Copposite/adjacent
Dhypotenuse/opposite
CBSEClass 10 (CBSE)MathematicsCh 8 · Topic 1
Trigonometric Ratios
Learning to define sine, cosine and tangent using a right triangle's sides.
Core concept
These three primary ratios have three corresponding reciprocal ratios: cosec θ = 1/sin θ, sec θ = 1/cos θ, and cot θ = 1/tan θ. Trigonometric ratios remain constant for a given angle regardless of the specific right triangle's size, since all right triangles with the same acute angle are similar to each other (by AA similarity), making these ratios a reliable, universal tool for solving problems involving angles and distances.
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• sin θ = opposite/hypotenuse. cos θ = adjacent/hypotenuse. tan θ = opposite/adjacent.
• Reciprocal ratios: cosec θ = 1/sin θ, sec θ = 1/cos θ, cot θ = 1/tan θ.
• Trigonometric ratios stay constant for a given angle, regardless of the triangle's size.
• This constancy follows from all right triangles with the same acute angle being similar (AA).