# math/ geometry.

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the vertex angle of an isoceles triangle is 120. the base length is 18. what is the length of the altitude to the base in simplest form

• math/ geometry. -

tan(120°/2)=(18/2)/h

tan(60°)=9/h

h=9/tan(60°)=9*ctg(60°)

h=9/sqroot(3)

9=3*sqroot(3)*sqroot(3)

h=3*sqroot(3)*sqroot(3)/sqroot(3)

h=3*sqroot(3)

h=5.1961524227

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