What is the length of ef¯¯¯¯¯? enter your answer as a decimal in the box. round only your final answer to the nearest tenth. ft a horizontally-aligned scalene triangle d e f. side d e is labeled as 6 feet. side d f is labeled as 11 feet. angle d is labeled as 40 degrees.

When finding the third side of a scalene triangle, use Law of Cosine with its formula

c^2 = A^2+B^2 - 2AB(cosC)

Now, you just have to input all your data in the formula, 

c^2 = 6^2+11^2 - 2(6)(11)(cos40degrees)
c^2 = 36+121 - 2(6)(11)(cos40degrees)
c^2 = 36+121 - 2(6)(11)(0.77)
c^2 = 157 - 101.12
c^2 = 55.88
c = square root of 55.88
c = 7.48 ft

Length of EF is 7.48 ft