anonymous050
anonymous050 anonymous050
  • 03-08-2019
  • Mathematics
contestada

In △ABC,a=14, b=17, and c=22. Find m∠A.

Respuesta :

gmany
gmany gmany
  • 03-08-2019

Answer:

[tex]\large\boxed{m\angle A\approx39^o}[/tex]

Step-by-step explanation:

Use the cosine law:

[tex]a^2=b^2+c^2-2bc\cos A[/tex]

We have:

[tex]a=14,\ b=17,\ c=22[/tex]

Substitute:

[tex]14^2=17^2+22^2-2(17)(22)\cos A\\\\196=289+484-748\cos A\\\\196=773-748\cos A\qquad\text{subtract 773 from both sides}\\\\-577=-748\cos A\qquad\text{divide both sides by (-748)}\\\\\cos A=\dfrac{577}{748}\\\\\cos A\approx0.7714\to m\angle A\approx39^o[/tex]

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