Question

Which expression can be used to find measure angle R

Answer 1

Answer:

cos-1(-4/14)

Step-by-step explanation:

If

4.5=r

3.5=s

2=t

By law of cosines:

$r^{2}=s^{2}+t^{2} -2st cosR\\\\CosR= \frac{r^{2} -s^{2} -t^{2} }{-2st} \\\\R=cos^{-1} (\frac{(4.5)^{2}-3.5^{2} -2^{2} }{-2(3.5)(2)} )\\R= cos^{-1} (-\frac{4}{14} )$