Question

Help me please! a = 3, b = 5, and c = 7. What is m&Bº to the nearest tenth?

Answer 1

Answer: m∡B°=38,2°.

Step-by-step explanation:

a=3,  b=5,  c=7  ∡B°=?

$b^2=a^2+c^2-2*a*ccosB^0\\2*a*c*cosB^0=a^2+c^2-b^2\\cosB^0=\frac{a^2+c^2-b^2}{2*a*c} \\cosB^0=\frac{3^2+7^2-5^2}{2*3*7} \\cosB^0=\frac{9+49-25}{2*3*7} \\cosB^0=\frac{33}{42} \\cosB^0=\frac{11}{14}$

m∡B°=arccos$(\frac{11}{14})$

m∡B°≈38,2°.

Good luck!