Given:
Given that the measure of ∠A is 74°
The length of side b is b = 6.
The length of side c is c = 5.
The length of side BC is a.
We need to determine the value of BC.
Value of BC:
The value of BC can be determined using the law of cosine formula.
Thus, we have;
![a^2=b^2+c^2-2bc \ cos (A)](https://img.qammunity.org/2021/formulas/mathematics/high-school/ax467sn0oposzyguf1mdcfjepgeoxs4v5c.png)
Substituting b = 6, c = 5 and ∠A = 74°, we get;
![a^2=6^2+5^2-2(6)(5) \ cos \ 74^(\circ)](https://img.qammunity.org/2021/formulas/mathematics/high-school/pnruh6xicvvit3gkdu34ppzqoh44ogm0vj.png)
![a^2=36+25-2(30)(0.28)](https://img.qammunity.org/2021/formulas/mathematics/high-school/bueevge08btlc93xttyjm5plv6ois4hts8.png)
![a^2=36+25-16.8](https://img.qammunity.org/2021/formulas/mathematics/high-school/6bwm2fic8n4lki15ewsof8xq1s86wsjys8.png)
![a^2=44.2](https://img.qammunity.org/2021/formulas/mathematics/high-school/eghq4pize70se1ewnss9rr9j3mz19rfdvs.png)
![a=6.6](https://img.qammunity.org/2021/formulas/mathematics/high-school/u87pvuedy82aglj9ldqbmi3l1buwi6wx0n.png)
Thus, the length of BC is 6.6 units.