tolong jawab dengan caranya

3) panjang busur = (α° / 360°) x 2 π r
                   7,85  = ( 22,5° / 360° ) 2 x 3,14 x r
                   7,85  =  0,39 x r
                        r   =  7,85 / 0,39
                            =  20 cm
    Luas lingkaran = π r²
                            = 3,14 x 20²
                            = 1.256 cm²

4) panjang busur = (α° / 360°) 2 π  r
                  132    = (84° / 360°) 2 x 3,14 x r
                   132   = 1,466 x r
                        r   = 132 / 1,466
                            =  90, 04 cm

    Luas lingkaran = π r²
                            = 3,14 x 90,04²
                            = 25.457,14 cm²