A triangle 7

A triangle lot has the dimensions a=15m, b=10m, and c=20m. What is the measure of the angle between the sides of b and c?

Correct answer:

α =  46.5675 °

Step-by-step explanation:

a=15 m b=10 m c=20 m  c2​=a2+b2​=152+102​=5 13​ m≐18.0278 m c2​​= c  a2=b2+c2 − 2⋅ b⋅ c⋅ cos α  α=π180°​⋅arccos(2⋅ b⋅ cb2+c2−a2​)=π180°​⋅arccos(2⋅ 10⋅ 20102+202−152​)=46.5675∘=46°34′3"

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