Nδdef, de = 11, ef = 9, and angle e = 140°. which equation correctly uses the law of cosines to solve for the third side?

Step-by-step explanation:

Please find the attachment.

We have been given that in ΔDEF, DE = 11, EF = 9, and angle E = 140°. We are asked to determine the equation that can be used to find the length of third side using law of cosines.

We can use Law of cosines to solve for a side of triangle, when we are given other two sides of the triangle and angle corresponding the side we need to figure out.

We can see from our attachment that e is side corresponding to angle 140 degrees, so to find the length of we can set an equation as:

Upon substituting our given values we will get,

Therefore, the equation can be used to find the length of third side.

Let us solve for third side.

Let us take square root of both sides of our equation.

Therefore, the length of 3rd side of triangle DEF is 18.81.

e2 = 112 + 92 − 2(11)(9)cos(140°)

i did the assignment   i hope this helps some!   :)

Step-by-step explanation:

Triangle D E F is shown. Angle D E F is 140 degrees. The length of D E is 11, the length of E F is 9, and the length of D F is e.

In ΔDEF, DE = 11, EF = 9, and angle E = 140°.

Which equation correctly uses the law of cosines to solve for the third side?

e2 = 112 + 92 − 2(11)(9)cos(140°)

112 = e2 + 92 − 2e(9)cos(140°)

92 = e2 + 112 − 2e(11)cos(140°)

e = 11 + 9 − 2(11)(9)cos(140°)

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step-by-step explanation: