Question

The lengths of the sides of a triangle are 25, 29, and 34. To the nearest tenth of a degree, the measure of the largest angle is

• A. ${77.6}^o$
• B. ${77.7}^o$
• C. ${87.6}^o$
• D. ${87.7}^o$
• E. ${102.3}^o$

Answer 1

The correct option is B ${77.7}^o$

Angle opposite to longest side will be largest.

$\Rightarrow \cos A=\frac{b^2+c^2-a^2}{2bc}=\frac{{25}^2+{29}^2-{34}^2}{2\times 25\times 29}$

$A=77.7°$