𝒑𝒈 𝟐𝟏𝟎 − 𝟐𝟏𝟐
𝒂𝒏𝒈𝒍𝒆
𝒍𝒆𝒏𝒈𝒕𝒉
𝒍𝒆𝒏𝒈𝒕𝒉
𝒑𝒈 𝟐𝟏𝟔
𝒂𝒏𝒈𝒍𝒆
𝒍𝒆𝒏𝒈𝒕𝒉
𝟐. 𝟔𝟖𝟗𝟕
𝟒 𝟑
𝒑𝒈 𝟐𝟏𝟎 − 𝟐𝟏𝟐
𝒂𝒏𝒈𝒍𝒆
𝒍𝒆𝒏𝒈𝒕𝒉
𝒑𝒈 𝟐𝟏𝟎 − 𝟐𝟏𝟑
𝒂𝒏𝒈𝒍𝒆
?
𝒑𝒈 𝟐𝟏𝟒
𝐬𝐢𝐧 𝐁 =
𝒔𝒊𝒏 𝟏𝟓𝟎 °
𝟏𝟖
× 𝟐𝟎
=
𝟓
𝟗
𝐁 = 𝟑𝟑. 𝟕𝟓 𝐨𝐫 𝟏𝟒𝟔. 𝟐𝟓
∴ 𝐧𝐨 𝐬𝐨𝐥𝐮𝐭𝐢𝐨𝐧 𝐚𝐬 𝐭𝐡𝐢𝐬 𝐭𝐫𝐢𝐚𝐧𝐠𝐥𝐞 𝐝𝐨𝐞𝐬 𝐧𝐨𝐭 𝐞𝐱𝐢𝐬𝐭.
𝒑𝒈 𝟐𝟏𝟔
𝒂𝒏𝒈𝒍𝒆
𝒍𝒆𝒏𝒈𝒕𝒉
𝑩 = 𝟑𝟓 ° 𝟏𝟔′ 𝐜 = 𝟏𝟕. 𝟐𝟓
𝑪 = 𝟖𝟒 ° 𝟒𝟒′
𝒔𝒊𝒏 𝑨 =
𝟐𝟓
𝟐𝟐
> 𝟏 𝒏𝒐 𝒔𝒐𝒍𝒖𝒕𝒊𝒐𝒏
𝑨 = 𝟗𝟕 ° 𝟏𝟖′ 𝑩 = 𝟓𝟕 ° 𝟒𝟐′ 𝐚 = 𝟒𝟔. 𝟗𝟒
𝑨 = 𝟑𝟐 ° 𝟒𝟐′ 𝑩 = 𝟏𝟐𝟐 ° 𝟏𝟖′ 𝐚 = 𝟐𝟓. 𝟓𝟕
𝒔𝒊𝒏 𝑩 = 𝟏. 𝟑𝟔 > 𝟎 𝒏𝒐 𝒔𝒐𝒍𝒖𝒕𝒊𝒐𝒏
𝑨 = 𝟏𝟒 ° 𝟐𝟗′ 𝑩 = 𝟔𝟐 ° 𝟕′ 𝐜 = 𝟏𝟏. 𝟎𝟏
𝑨 = 𝟏𝟒 ° 𝟐𝟗′ 𝑩 = 𝟏𝟏𝟕 ° 𝟓𝟑′ 𝐜 = 𝟖. 𝟑𝟔
𝑪 = 𝟏𝟎𝟑 ° 𝟐𝟒′
𝑪 = 𝟒𝟕 ° 𝟑𝟖′
𝑩 = 𝟒𝟓 ° 𝐜 = 𝟑. 𝟖𝟔 cm
𝑩 = 𝟏𝟑𝟓 ° 𝐜 = 𝟏. 𝟎𝟔 𝐜𝐦
𝑪 = 𝟏𝟎𝟓 ° 𝟕′
𝑪 = 𝟏𝟓 °
𝒑𝒈 𝟐𝟏𝟔
𝒂𝒏𝒈𝒍𝒆
𝒍𝒆𝒏𝒈𝒕𝒉
𝑨 = 𝟕𝟎 ° 𝟏𝟐′ 𝑩 = 𝟓𝟕 ° 𝟐𝟒′ 𝐛 = 𝟐𝟖. 𝟕𝟗 𝐜𝐦
𝑨 = 𝟏𝟎𝟗 ° 𝟒𝟖′ 𝑩 = 𝟏𝟕 ° 𝟒𝟖′
𝐚 = 𝟕. 𝟓𝟑 𝐜𝐦 𝐛 = 𝟓. 𝟏𝟔 𝐜𝐦 𝑪 = 𝟖𝟑 ° 𝟑𝟗′
𝐛 = 𝟏𝟎. 𝟒𝟓 𝐜𝐦
两边为 𝟓𝟎. 𝟔𝟑 𝒄𝒎, 𝟔𝟎. 𝟒𝟒 𝒄𝒎
𝑨𝒓𝒆𝒂 = 𝟑𝟎𝟓𝟒 𝒄𝒎𝟐
𝐚 = 𝟕. 𝟑𝟗 𝐜𝐦 𝐛 = 𝟏𝟑. 𝟖𝟗 𝐜𝐦
𝟖𝟏. 𝟒𝟔 cm
𝐜 = 𝟏𝟖. 𝟕𝟐 𝐜𝐦
𝒑𝒈 𝟐𝟏𝟔 − 𝟐𝟏𝟖
𝒍𝒆𝒏𝒈𝒕𝒉
𝒂𝒏𝒈𝒍𝒆
b
𝒑𝒈 𝟐𝟐𝟏
𝒍𝒆𝒏𝒈𝒕𝒉
𝒂𝒏𝒈𝒍𝒆
𝟗𝟎 °
𝟕 𝒄𝒎 𝟗𝟖 ° 𝟏𝟑′
𝒑𝒈 𝟐𝟏𝟗
𝒍𝒆𝒏𝒈𝒕𝒉
𝒂𝒏𝒈𝒍𝒆
𝒑𝒈 𝟐𝟏𝟗 − 𝟐𝟐𝟎
𝒑𝒈 𝟐𝟐𝟏
𝒍𝒆𝒏𝒈𝒕𝒉
𝒂𝒏𝒈𝒍𝒆
𝑨 = 𝟐𝟏 ° 𝟒𝟕′ 𝑩 = 𝟖 ° 𝟏𝟑′ 𝑪 = 𝟏𝟓𝟎 °
𝑨 = 𝟓𝟗 ° 𝟐𝟗′ 𝑩 = 𝟗𝟎 ° 𝑪 = 𝟑𝟎 ° 𝟑𝟏′
𝑨 = 𝟑𝟔 ° 𝟐𝟑′ 𝒃 = 𝟔𝟖. 𝟖𝟓 𝑪 = 𝟓𝟖 ° 𝟑𝟕′
𝒂 = 𝟔𝟐. 𝟑𝟏 𝑩 = 𝟑𝟓 ° 𝟓𝟒′ 𝑪 = 𝟑𝟖 ° 𝟔′
𝑨 = 𝟒𝟓 ° 𝑩 = 𝟑𝟎 ° 𝑪 = 𝟏𝟎𝟓 °
𝑨 = 𝟒𝟒 ° 𝟒𝟐′ 𝑩 = 𝟓𝟕 ° 𝟑𝟔′ 𝒄 = 𝟕𝟕. 𝟏𝟓 cm
𝟏𝟎𝟒 ° 𝟐𝟗′
𝟐. 𝟎𝟕 𝒙 𝟒𝟏 ° 𝟑𝟕′
𝟑𝟎 °
𝒑𝒈 𝟐𝟐𝟏
𝒍𝒆𝒏𝒈𝒕𝒉
𝒂𝒏𝒈𝒍𝒆
𝑐𝑜𝑠 𝐴 =
𝑏2 + 𝑐2 − 𝑎2
2𝑏𝑐
=
2
2
+ 3 + 1
2
− 22
2 × 2 × 3 + 1
=
2 + 3 + 2 3 + 1 − 4
2 2 3 + 1
=
2 + 2 3
2 2 3 + 1
=
2 1 + 3
2 2 3 + 1
𝐴 = 45 °
𝑠𝑖𝑛 𝐵
𝑏
=
𝑠𝑖𝑛 𝐴
𝑎
𝑠𝑖𝑛 𝐵 =
𝑠𝑖𝑛 𝐴
𝑎
× 𝑏
=
𝑠𝑖𝑛 45 °
2
× 2
𝐵 = 30 °
𝐶 = 180 ° − (𝐴 + 𝐵)
= 180 ° − (45 ° + 30 °)
𝐶
= 105 °
𝒑𝒈 𝟐𝟐𝟏
𝒍𝒆𝒏𝒈𝒕𝒉
𝒂𝒏𝒈𝒍𝒆
𝑠𝑖𝑛 𝐴
𝑎
=
𝑠𝑖𝑛 𝐵
𝑏
𝑠𝑖𝑛 𝐴 =
𝑠𝑖𝑛 𝐵
𝑏
× 𝑎
=
𝑠𝑖𝑛 95 °
3𝑥
× 2𝑥
𝐴 = 41 ° 37’
= 0.6641
𝐶 = 180 ° − (𝐴 + 𝐵)
= 180 ° − (41 °37’ + 95 °)
= 43.38 °
𝑐2 = 𝑎2 + 𝑏2 − 2𝑎𝑏 𝑐𝑜𝑠 𝐶
= (2)2
+(3𝑥)2
− 2 2𝑥 3𝑥 𝑐𝑜𝑠 43.38 °
= 13𝑥2
− 8.72𝑥2
c = 2.07 𝑥
𝒑𝒈 𝟐𝟐𝟏
𝒍𝒆𝒏𝒈𝒕𝒉
𝒂𝒏𝒈𝒍𝒆
𝒂: 𝒃: 𝒄 = 𝟕 ∶ 𝟔. 𝟗𝟑 ∶ 𝟑. 𝟔𝟏
𝑐𝑜𝑠 𝐶 =
𝑎2 + 𝑏2 − 𝑐2
2𝑎𝑏
=
72 + (4 3)2−( 13)2
2 × 7 × 4 3
𝐶 = 30 °
𝒑𝒈 𝟐𝟐𝟏
𝒍𝒆𝒏𝒈𝒕𝒉
𝒂𝒏𝒈𝒍𝒆
𝟏𝟎𝟏. 𝟕𝟑 𝒄𝒎
𝟖𝟐 ° 𝟒𝟗′
𝒑𝒈 𝟐𝟐𝟏
𝒍𝒆𝒏𝒈𝒕𝒉
𝒂𝒏𝒈𝒍𝒆
𝟐
𝟑
𝟐. 𝟓
?
𝟐. 𝟓
∆ 𝑨𝑩𝑪
𝑐𝑜𝑠 𝐵 =
𝑎2 + 𝑐2 − 𝑏2
2𝑎𝑐
=
(2.5)2
+22
− 32
2 × 2.5 × 2
𝑎𝑛𝑔𝑙𝑒 𝐶𝐵𝐴 = 82 ° 49’
𝒑𝒈 𝟐𝟐𝟏
𝒍𝒆𝒏𝒈𝒕𝒉
𝒂𝒏𝒈𝒍𝒆
𝟑𝟗. 𝟑𝟐 𝒄𝒎 𝟐𝟖. 𝟎𝟎 𝒄𝒎
𝒂
𝒃
𝒄
𝑩𝑸𝟐
= 𝑨𝑸𝟐
+ 𝒄𝟐
− 𝟐𝒂𝒄 𝒄𝒐𝒔 𝑨
= (𝟑𝟗. 𝟑𝟐)𝟐
+(𝟐𝟒. 𝟒𝟗)𝟐
− 𝟐 𝟑𝟗. 𝟑𝟐 𝟐𝟒. 𝟒𝟗 𝒄𝒐𝒔 𝟒𝟓 °
𝒂
𝒔𝒊𝒏 𝑨
=
𝒃
𝒔𝒊𝒏 𝑩
=
𝒄
𝒔𝒊𝒏 𝑪
𝐛 =
𝟐𝟎
𝒔𝒊𝒏 𝟒𝟓 °
× 𝒔𝒊𝒏 (𝟏𝟖𝟎 − 𝟏𝟎𝟓) °
= 𝟐𝟕. 𝟑𝟐 𝐜𝐦
𝐀𝐐 = 𝟐𝟕. 𝟑𝟐 + 𝟏𝟐 = 𝟑𝟗. 𝟑𝟐 𝐜𝐦
∆ 𝑨𝑩𝑪
𝐜 =
𝟐𝟎
𝒔𝒊𝒏 𝟒𝟓 °
× 𝒔𝒊𝒏 (𝟏𝟎𝟓 − 𝟒𝟓) °
= 𝟐𝟒. 𝟒𝟗 𝐜𝐦
∆ 𝑨𝑩𝑸
𝑩𝑸 = 𝟐𝟖. 𝟎𝟎 𝒄𝒎
𝒑𝒈 𝟐𝟐𝟎
𝒍𝒆𝒏𝒈𝒕𝒉
𝒂𝒏𝒈𝒍𝒆

SUEC 高中 Adv Maths (Sin and Cos Rule)

Editor's Notes

  • #2 https://www.onlinemathlearning.com/triangle-questions.html
  • #3 https://www.onlinemathlearning.com/triangle-questions.html
  • #4 https://www.onlinemathlearning.com/triangle-questions.html
  • #9 3. one diagonal of the parallelogram is 76.33 cm long, and this diagonal forms an angle A and B with the two sides respectively.
  • #12 https://www.onlinemathlearning.com/cosine-rule.html
  • #20 5. A = 28.96 degree, B = 180 – A = 151.04 degree