Question

Find the approximate value of $\angle A$ in $\Delta ABC$ if $8\angle A=9\angle B=4\angle C$

• A. ${40}^o$
• B. ${74}^o$
• C. ${86}^o$
• D. ${46.3}^o$

Answer 1

The correct option is D ${46.3}^o$

Let $\angle A=x$

$\angle B=\frac{8}{9}x$

$\angle C=\frac{8}{4}x=2x$

Using angle sum property

$x+\frac{8}{9}x+2x={180}^{\circ }\frac{9x+8x+18x}{9}={180}^{\circ }\frac{35x}{9}={180}^{\circ }\Rightarrow x={46.28}^{\circ }$