CH is an altitude of ACE
m

If you mean stuff like  : if you're using microsoft word, you can try looking in the equation editor, under brackets, and then common brackets. i can confirm this is true for word 2016.if you're using latex (microsoft word also has latex apparently), then probably the command    \binom{a}{b}is your best bet.the print out for \binom{a}{b} is  if you want it bigger, you can use     \dbinom{a}{b} or  \displaystyle\binom{a}{b}the print out of \dbinom{a}{b} is  more examples: \dbinom{n-1}{k,n-k}    \dbinom{n}{p_1,p_2,p_3}