lesson
Using the Pythagorean Identity to Find cos(θ) Given sin(θ)
Apply the identity sin²(θ) + cos²(θ) = 1 to find cosine when sine is known, determining the correct sign by quadrant.
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The Pythagorean Identity and Real-World Trigonometry
4 lessons
Goal
Apply the Pythagorean identity to find trigonometric values from known values, and use trigonometric ratios to solve real-world problems involving angles of elevation and depression.
4 lessons
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Learning standards covered
111.41(b)(9)(A)Texas Essential Knowledge and Skills (TEKS) · Math · 10th Gradedetermine the lengths of sides and measures of angles in a right triangle by applying the trigonometric ratios sine, cosine, and tangent to solve problems; and
Open Global Standard:OGM.11.TRG.1
111.41(b)(1)(F)Texas Essential Knowledge and Skills (TEKS) · Math · 10th Gradeanalyze mathematical relationships to connect and communicate mathematical ideas; and
Open Global Standard:OGM.11.GEO.1
OGM.11.TRG.1OGM.11.GEO.1