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Perhatikan gambar di samping. Diketahui  siku...

Perhatikan gambar di samping.



Diketahui begin mathsize 14px style increment ABC end style siku-siku di B dengan panjang size 14px AC size 14px equals size 14px 40 size 14px space size 14px cm dan size 14px BC size 14px equals size 14px 24 size 14px space size 14px cm. Titik D terletak pada AB sedemikian sehingga size 14px CD size 14px equals size 14px 25 size 14px space size 14px cm. Panjang begin mathsize 14px style AD equals... space cm end style

Jawaban:

Perhatikan segitiga ABC!

Karena segitiga ABC merupakan segitiga siku-siku, maka gunakan teorema Pythagoras untuk menentukan panjang AB.

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell AC squared end cell equals cell AB squared plus BC squared end cell row cell AB squared end cell equals cell AC squared minus BC squared end cell row cell AB squared end cell equals cell 40 squared minus 24 squared end cell row cell AB squared end cell equals cell 1.600 minus 576 end cell row cell AB squared end cell equals cell 1.024 end cell row AB equals cell plus-or-minus square root of 1.024 end root end cell row AB equals cell plus-or-minus 32 space cm end cell end table end style 

Karena panjang sisi AB tidak mungkin negatif, maka pilih table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px AB end table table attributes columnalign right center left columnspacing 0px end attributes row blank size 14px equals blank end table table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px 32 end table table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px space end table table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px cm end table.

Perhatikan segitiga DBC!

Karena segitiga DBC merupakan segitiga siku-siku, maka gunakan teorema Pythagoras untuk menentukan panjang DB.

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell CD squared end cell equals cell DB squared plus BC squared end cell row cell straight D straight B squared end cell equals cell CD squared minus BC squared end cell row cell straight D straight B squared end cell equals cell 25 squared minus 24 squared end cell row cell straight D straight B squared end cell equals cell 625 minus 576 end cell row cell straight D straight B squared end cell equals 49 row cell straight D straight B end cell equals cell plus-or-minus square root of 49 end cell row cell straight D straight B end cell equals cell plus-or-minus 7 space cm end cell end table end style  

Karena panjang sisi DB tidak mungkin negatif, maka pilih table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px DB end table table attributes columnalign right center left columnspacing 0px end attributes row blank size 14px equals blank end table table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px 7 end table table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px space end table table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px cm end table.

Sehingga, panjang AD:

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row AD equals cell AB minus DB end cell row blank equals cell 32 minus 7 end cell row blank equals cell 25 space cm end cell end table end style

Jadi, panjang table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px AD end table table attributes columnalign right center left columnspacing 0px end attributes row blank size 14px equals blank end table table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px 25 end table table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px space end table table attributes columnalign right center left columnspacing 0px end attributes row blank blank size 14px cm end table.

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