whongaliemdikerjakan no.20 dan 25 atas permintaan pembuat soal
20) ∠ P = ∠ Q (bertolak belakang) 1/4 x + 60° = 2x - 10° 60° + 10° = 2x - 1/4 x 70° = 7/4 x x = 70° . 4/7 x = 40° ∠ P = 1/4 x + 60° = 1/4 .40° + 60° = 10° + 60° = 70° segitiga sama sisi dengan salah satu sudut R ⇒ R = 60° ∠ R = ∠ P - ∠ S 60° = 70° - ∠ S ∠ S = 70° - 60° = 10°
20) ∠ P = ∠ Q (bertolak belakang)
1/4 x + 60° = 2x - 10°
60° + 10° = 2x - 1/4 x
70° = 7/4 x
x = 70° . 4/7
x = 40°
∠ P = 1/4 x + 60°
= 1/4 .40° + 60°
= 10° + 60°
= 70°
segitiga sama sisi dengan salah satu sudut R ⇒ R = 60°
∠ R = ∠ P - ∠ S
60° = 70° - ∠ S
∠ S = 70° - 60°
= 10°
25) PR = √(PQ² + RQ²)
= √(18² + 24²)
= √(324 + 576)
= √900
= 30 cm
⇒ TR = 2/3 x 30
= 20 cm
tarik garis bantu SO⊥ PR
SR² = RO . RP
18² = RO . 30
324 = RO . 30
RO = 324 / 30
RO = 108 / 10
⇒ TO = 20 - 108/10
= 92/10
SO² = RO . OP
= 108/10 . (30 - 108/10)
= 108/10 . 192/10
= 20736/100
ST² = SO² + TO²
= 20736/100 + (92/10)²
= 20736/100 + 8464/100
= 29200/100
= 292
ST = √292
= √4 .√73
= 2√73
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