Help with Double Angle Identities

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    Angle identities
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SUMMARY

The discussion focuses on solving for sin2θ given cos θ = 24/25, with the angle θ located in the first quadrant (0<θ<90). To find sin2θ, users should utilize the double angle identity sin2θ = 2sinθcosθ. The solution involves first calculating sin θ using the Pythagorean theorem, resulting in sin θ = 7/25. Substituting these values into the double angle formula yields sin2θ = 2 * (7/25) * (24/25), which simplifies to 339/625.

PREREQUISITES
  • Understanding of trigonometric identities, specifically double angle formulas.
  • Familiarity with the Pythagorean theorem.
  • Knowledge of sine and cosine functions.
  • Ability to sketch right-angled triangles for visual aid.
NEXT STEPS
  • Study the derivation of double angle identities in trigonometry.
  • Practice problems involving the Pythagorean theorem in trigonometric contexts.
  • Explore additional trigonometric identities, such as sum and difference formulas.
  • Learn how to apply trigonometric identities in real-world applications.
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Students studying trigonometry, educators teaching trigonometric identities, and anyone looking to strengthen their understanding of angle relationships in mathematics.

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Help with Double Angle Identities!

cos θ = 24/25

The angle lies in quadrant 1; 0<θ<90

Find sin2θ



I know you would use either the formula cos^2θ - sin^2θ or 2sinθcosθ
And I know that the answer is 339/625, but I do not know how to get that answer?
 
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Use trig formulae and Pythagoras.
It helps if you sketch the angle in a rt-angled triangle.
 


hint: first find sin θ
 

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