
3-7 Finding side lengths and complementary angles
Point 7 of 11 — Unit 3: Similarity, Dilation, Trigonometric Ratios and the Straight LineQuestion bank: 0 questions (0 with pictures)
07 3-7 Finding side lengths and complementary angles
- Choose the ratio that links the known side with the unknown one, substitute and solve; use Pythagoras when two sides are known.
- Example: hypotenuse 10 and angle 30° → opposite = 10 sin 30° = 5, adjacent = 10 cos 30° = 5√3.
- Two acute angles in a right triangle are complementary (they sum to 90°), hence sinθ = cos(90 − θ), cosθ = sin(90 − θ) and tanθ = cot(90 − θ).
- So a ratio given for one angle can be read off for its complement — a standard one-mark conversion.
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