The side lengths of 11 cm, 2 cm and 13 cm can or cannot form a triangle

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since the cosine is the ratio of the adjacent side to the hypotenuse, you can see that cos 60° = ½. answer. according to the property of cofunctions (topic 3), sin 30° is equal to cos 60°. sin 30° = ½.

If this is the question f(x)= -x2 +4x-3 f(-1)= )2 +4 (-1)-3 =2-4-3 f(-1) =-5