In ΔABC, given that a=9.5, b=10.7cm and c=12.4cm find angle B.
2006-12-16 16:11:05 · 7 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Cosine Rule
Cos Angle B = (c^2 + a^2 - b^2)/2ac
Angle B = Cos^-1 (0.54974)
= 56.7 degrees
2006-12-16 16:17:12 · answer #1 · answered by PIPI B 4 · 0⤊ 0⤋
Use the regulation of cosines. c^2 = a^2 + b^2 -2ab(cosC) Plug in 26 for c, 18 for b, and 17 for a. 676 = 324 + 280 - 612*cosC cosC = -7/sixty 8 C = ninety 5.9 tiers Do it back for b. 324 = 676 + 280 - 884cosB B = 40 4.4 tiers. by using fact the angles of a triangle upload as much as one hundred eighty tiers, locate the attitude A with this equation: one hundred eighty - 40 4.4 - ninety 5.9 = A hence, A = 39.7, B = 40 4.4, and C = ninety 5.9
2016-10-15 02:34:18 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Applying cosine rule,
b² = a² + c² - 2ac cos
2006-12-17 04:34:08 · answer #3 · answered by Ranna Renni 2 · 0⤊ 1⤋
Use law of cosines
10.7^2=9.5^2+12.4^2-2*9.5*12.4*cos B
-cos B=(10.7^2-9.5^2-12.4^2)/(2*9.5*12.4)=-0.5497453310696095
B=arccos 0.54974533106960950764006791171477
B=56.65°
2006-12-16 17:25:29 · answer #4 · answered by yupchagee 7 · 0⤊ 1⤋
Hey how did you make that triangle symol? You have to used either the sine law or cosine law if I remember correctly.
2006-12-16 16:14:54 · answer #5 · answered by mojo2093@sbcglobal.net 5 · 0⤊ 0⤋
use the cosine rule
a^2+c^2-b^2=2accosB
2006-12-16 16:17:35 · answer #6 · answered by raj 7 · 1⤊ 0⤋
Omg that remind me how much I hate math
2006-12-16 16:18:12 · answer #7 · answered by newbie 1 · 0⤊ 0⤋