Jawaban:

Jarak kedua pusat lingkaran begin mathsize 14px style equals straight p equals 20 blank cm end style

Panjang garis singgung persekutuan dalam undefined

begin mathsize 14px style straight R equals 10 space cm end style

mencari undefined

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell straight d squared end cell equals cell straight p squared minus left parenthesis straight R plus straight r right parenthesis squared end cell row cell 16 squared end cell equals cell 20 squared minus left parenthesis straight R plus straight r right parenthesis squared end cell row cell left parenthesis straight R plus straight r right parenthesis squared end cell equals cell 400 minus 256 end cell row blank equals 144 row cell straight R plus straight r end cell equals cell plus-or-minus √ 144 end cell end table end style

Karena panjang sisi, maka jari-jari non negatif sehingga

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell straight R plus straight r end cell equals cell 12 space space space end cell row cell 10 plus straight r end cell equals cell 12 space space end cell row straight r equals cell 12 minus 10 space space end cell row straight r equals cell 2 space cm end cell end table end style