Question 1180132
It says the third side, r, has this relationship:  r = p + q
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Detailed steps:
r = {{{ sqrt(p^2 + q^2 - 2pq*cos(180^o)) }}} 
= {{{ sqrt(p^2+q^2 + 2pq) }}}
= {{{ sqrt((p+q)^2) }}}
= {{{ p+q }}}