Basic Formulas to Know 4

And remember similar triangles!

similar triangles

You can always use similar triangles to set up proportions:

( a / A ) = ( b / B ) = ( c / C )

or

( A / a ) = ( B / b ) = ( C / c )

Or, more commonly, you can mix and match like these:

( b / a ) = ( B / A )

or

( a / c ) = ( A / C )

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