Diketahui segitiga ABC dengan panjang sisi AB=6cm, BC=8cm, AC=7cm. Nilai cos A adalah...
Rohimthegunner
Menggunakan rumus cos (bc)² = (ac)² + (ab)² -2(ac).(ab).cos a 64 = 49 + 36 -2.7.6.cos a 64 = 85 - 84.cos a 84.cos a =85-64 84.cos a = 21 cos a = 21/84 cos a = 1/4
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ecis
(BC)² = (AB)² + (AC)² - 2(AB)(AC)cos A 64 = 36 + 49 - (2)(6)(7) cos A 64 = 85 - (84) cos A (84) cos A = 85 - 64 (84) cos A = 21 cos A = 21/84 cos A = 1/4
(bc)² = (ac)² + (ab)² -2(ac).(ab).cos a
64 = 49 + 36 -2.7.6.cos a
64 = 85 - 84.cos a
84.cos a =85-64
84.cos a = 21
cos a = 21/84
cos a = 1/4
64 = 36 + 49 - (2)(6)(7) cos A
64 = 85 - (84) cos A
(84) cos A = 85 - 64
(84) cos A = 21
cos A = 21/84
cos A = 1/4