Question

Tolong bantuan nya ya..
jelasin jalannya juga ya..

Answer 1

Pakai perbandingan sudut dan panjang busur.

diket < AOB = 50'
panjang busur AB = 30cm
< COB = 180 - 50 = 130'
ditanya panjang busur BC...?
<AOB/<COB = panjang busur AB/panjang busurBC
50/130 = 30/BC
BC = 130 x 30 / 50
BC = 78cm

Answer 2

Busur = besar sudut AB/360 x 2 x pi x r
    30 = 50/360 x 2 x 3,14 x r
    30 = 50/180 x 3,14 xr
    30 = 5/18 x 3,14 x r
    30 = 15,7 / 18 x r
      r = 30 : 15,7/18
     r  = 30 x 18 / 15,7
        = 540 / 15,7
        = 34,39
180 - 50 = 130°
sudut BC = 130°
panajang busur BC = 130/360 x 2 x 3,14 x 34,39
                            = 13/36 x 2 x 3,14 x 34,39
                            = 13 / 18 x 3,14 x 34,39
                            = 13 / 18 x 107,9846
                            = 13 x 5,999
                            = 77,987 cm²