How should I do this question that is in the image below?42

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Answer 1 · 2018-01-27T13:56:07

Using cosine rule,

#color(green)(/_B = 98.1289^0)#

enter image source here

#c = sqrt((6-2)^2 + (2-5)^2) = sqrt(25) = 5#

#a = sqrt((2+6)^2 + (5+3)^2) = sqrt(128) = 8sqrt2#

#b = sqrt((6+6)^2 + (2+3)^2) = sqrt(169) = 13#

Three sides are #c = 5, a = 8sqrt2, b = 13#

Largest side will have largest angle opposite to it.

Let’s apply cosine rule to find the largest angle B

#cos B = (c^2 + a^2 - b^2) / (2ac) #

#cos B = (25 + 128 - 169) / (2 * 5 *8(sqrt2)) = -16 / 113.1371#

#cos B = -0.1414 #

#color(green)(/_B = 98.1289^0)#