a.) A= (1/2)absinC
b.) sinA/a, sinB/b, sinC/c
sin100/42, sin25/b, sinC/c
use these two fractions.
sin100/42= sin25/b
cross multiply next
b×sin100= 42×sin25
then divide on both sides by sin100
b=18
c.)measurementofA+measurementofB+measurementofC=180
100+25+C=180
125+C=180
-125 -125
The measurement of angle C is 55 degrees.
d.)A=(1/2)42×18×sin55
= 21×18×sin55
A =309.6 units squared