Question 698758
<pre>
This one for the case of SSS (all three sides known):
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             (ONE SIDE OF ANGLE)²+(OTHER SIDE OF ANGLE)²-(OPPOSITE SIDE OF ANGLE)² 
cos(ANGLE) = ---------------------------------------------------------------------
                      2×(ONE SIDE OF ANGLE)×(OTHER SIDE OF ANGLE)
</font>

cos(x) = {{{(5^2+9^2-6^2)/(2*5*6)}}}

cos(x) = {{{(25+81-36)/60}}}

Work that out, then use the inverse cosine
feature on your calculator to get

x = 38.9424127 or 38°56'32.789"

Edwin</pre>