silemus.
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  1. 9Similar triangles, shadows
  2. 10Similar triangles, area ratio
  3. 1230-60-90 triangle sides
  4. 14Angle of elevation, right triangle
  5. 18Inscribed angle theorem
  6. 19Angle in a semicircle
  7. 21Equal tangent lengths
  8. 22Chord distance from centre
  9. 26Interior angles of an octagon
  10. 30Area and side of a rhombus
  11. 31Prism volume and surface area
  12. 33Volume and slant height of cone
  13. 40Perpendicular bisector
  14. 41Area of triangle by coords
  15. 42Circle, completing the square

14Angle of elevation, right triangle

From a point 50 m from the foot of a building, the angle of elevation to the top is 28°. Find the height of the building. Give the answer to 1 decimal place.

The building is about 26.6 m tall. Using the right triangle with the 50 m distance as adjacent and height h as opposite, tan(28°) = h/50, so h = 50·tan(28°) ≈ 26.6 m. Checking: tan⁻¹(26.6/50) ≈ 28.0°.

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