Question

PLLLLLLLLLZ HELP 30 POINTS ANSWER ONLY IF YOU KNOW

An antelope trots 40 m east, then turns at a 45o angle and trots 70 m southeast. Which choice gives the correct solution for the resultant?


R^2 = 40^2 + 70^2


R^2 = 40^2 + 70^2 - 2(40)(70) cos 135°


R^2 = 70^2 - 40^2


R^2 = 40^2 - 70^2 - 2(40)(70) cos 45°(incorrect)

Answer 1

R^2 = 40^2 + 70^2 - 2(40)(70) cos 135°

Step-by-step explanation:

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Answer 2

R^2 = 40^2 + 70^2 - 2(40)(70) cos 135°

Step-by-step explanation:

The resultant connects the tail of the first vector to the head of the second vector (whose tail is at the head of the first vector). The three vectors form an obtuse triangle where the angle between the original direction and the second direction is 135°. The cosine factor in the Law of Cosines formula will be cos(135°), matching the second choice.