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°)

square pyramid

step-by-step explanation:

square prism looks like nothing like that

triangular prism has a rectangular base instead of a square base

tetrahedron has a triangular base

d) by the cross product property, ab^2 = bc multiplied by ad

step-by-step explanation:

we are given

in the given triangle abc

angle a is 90° and segment ad is perpendicular to segment bc

we can see that

triangle(abc) and triangle(abd) are similar because they have common side and same angle (90 degree)

so, triangles(abc) and abd are similar

since, they are similar

so, the ratio of their sides must be equal

we get

now, we can cross multiply

and we get

so, this could be step to prove it

if you was gonna solve for a, a is a   < -12