Q. In △ABC,AB=5cm,BC=6cm and ∠B=60∘.Find the length of AC.
Identify Elements and Rule: Identify the known elements of the triangle and the rule to apply.In triangle ABC, we know side AB (5cm), side BC (6cm), and angle B (60 degrees). To find the length of side AC, we can use the Law of Cosines, which relates the lengths of the sides of a triangle to the cosine of one of its angles.
Write Law of Cosines: Write down the Law of Cosines formula.The Law of Cosines states that for any triangle ABC with sides a, b, and c opposite angles A, B, and C respectively, the following is true: c2=a2+b2−2abcos(C). In our case, we want to find c (AC), where a0 (a1), a2 (a3), and angle C is a5 degrees.
Substitute Known Values: Substitute the known values into the Law of Cosines formula.Using the values we have, we get AC2=52+62−2×5×6cos(60 degrees). We know that cos(60 degrees) is 0.5.
Calculate AC Length: Calculate the length of AC.AC2=25+36−2×5×6×0.5AC2=25+36−30AC2=61−30AC2=31AC=31
Check for Errors: Check for any mathematical errors.We have correctly applied the Law of Cosines and performed the arithmetic operations. There are no mathematical errors in the calculations.
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