Биссектриса угла A и D прямоугольника ABCD делят сторону BC на три равные части точками M и N.

<span>__________$$$$$$$$______$$$$$$$$$, </span>
<span>__________$$$$$$$$$$$$__$$$$$$$__$$$$, </span>
<span>_________$$$$$$$$$$$$$$$$$$$$$$$$__$$$, </span>
<span>_________$$$$$$$$$$$$$$$$$$$$$$$$__$$$, </span>
<span>_Передай_$$$$$$$$$$$$$$$$$$$$$$$$__$$$, </span>
<span>__________$$$$$$$$$$$$$$$$$$$$$$__$$$, </span>
<span>__тому______$$$$$$$$$$$$$$$$$$$$$$$, </span>
<span>_______________$$$$$$$$$$$$$$$$$, </span>
<span>___кто___________$$$$$$$$$$$$$, </span>
<span>__тебе_дорог________$$$$$$$, </span>
<span>______________________$$$, </span>
<span>_______________________$</span>

tgA*ctgA = sinA/cosA x cosA/sinA =1