△ Trigonometry
Find a side when two sides and included angle known
Formula
Find a side when two sides and included angle known
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Law of Cosines (law of cosines) is a trigonometry relationship written as Find a side when two sides and included angle known or c² = a² + b² − 2ab cos C. Students use it to solve unknowns when enough values are known.
Write Find a side when two sides and included angle known, substitute the known numbers carefully, then simplify. Worked walkthrough: a=5, b=7, C=60° c² = 25+49−70×0.5 = 39 c ≈ 6.24.
Law of Cosines usually appears in trigonometry units during middle or secondary school. Match difficulty with MathDigits grade worksheets so practice fits the curriculum year.
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