Answer :
The vertex angle bisector divides the triangle into two congruent right triangles. The sine of half of the vertex angle will be half of the base divided by the side (from the definition of the sine of an angle). Then the total vertex angle is ...
α = 2×arcsin(3.5/5) ≈ 88.9°
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Using the Law of Cosines, the vertex angle can be found as
arccos((7^2 -5^2 -5^2)/(-2*5*5)) = arccos(1/50) ≈ 88.9°
α = 2×arcsin(3.5/5) ≈ 88.9°
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Using the Law of Cosines, the vertex angle can be found as
arccos((7^2 -5^2 -5^2)/(-2*5*5)) = arccos(1/50) ≈ 88.9°