Answer:
18.0 cm to 1 decimal point.
Step-by-step explanation:
First work out the unknown side (s) of the right triangle using the Pythagoras theorem:
s^2 = 13^2 - 5^2
= 169 - 25 = 144
s = sqrt 144 = 12 cm.
Now consider the other triangle:
s = 12
The missing angle = 180 - 65 - 40 = 75 degrees.
By the Sine Rule:
x / sin 75 = 12 / sin40
x = 12 sin 75 / sin 40
= 18.03
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