Dabour Hub EGEgyptian Curriculum 2026/2027
3-6 Sides relative to an angle, and the definitions of sin, cos and tan

3-6 Sides relative to an angle, and the definitions of sin, cos and tan

Point 6 of 11 — Unit 3: Similarity, Dilation, Trigonometric Ratios and the Straight LineQuestion bank: 0 questions (0 with pictures)

06 3-6 Sides relative to an angle, and the definitions of sin, cos and tan

  • In a right triangle, for an acute angle θ: the opposite side faces θ, the adjacent side touches it, and the hypotenuse lies opposite the right angle and is the longest side.
  • sinθ = opposite/hypotenuse, cosθ = adjacent/hypotenuse, tanθ = opposite/adjacent (SOH-CAH-TOA).
  • The ratios depend on the angle only, not on the size of the triangle — that is why similar triangles give the same values.
  • Because the hypotenuse is longest, sinθ and cosθ are always between 0 and 1 for an acute angle, while tanθ can be any positive number.
  • tanθ = sinθ/cosθ, and sin²θ + cos²θ = 1.

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