Step-by-step answer:
Given:
A triangle
Perimeter = 60 cm
longest side = 4* shortest side (x)
Solution:
longest side = 4x
shortest side = x
third (intermediate side = 60 -x -4x = 60-5x
The triangle inequality specifies that the sum of the two shorter sides must be greater than the longest side to form a triangle. Hence
x + y > 4x
x + 60-5x > 4x
60 - 4x > 4x
8x < 60
x < 60/8 = 7.5, or
x < 7.5
Therefore to form a triangle, x (shortest side) must be less than 7.5 cm.
Examine the options: both 7 and 5 are both less than 7.5 cm.
40, 30 and 25 all have a problem because the longest side (4 times longer) will exceed the perimeter of 60.
Now also examine cases where 4x is NOT the longest side, in which case we need
4x>=y
or
4x >= 60-5x
9x >=60
x >= 6.67
so x=5 will not qualify, because 4x will no longer be the longest side.
The only valid option is x=7 cm
The side lengths for x=7 and x=5 are, respectively,
(7, 25, 28)
5, 20, 35 (in which case, the longest side is no longer 4x=20, so eliminated)
14.4, if my calculator was correct
Answer:
A ≈ 119.7°, b ≈ 25.7, C ≈ 24.3°
Step-by-step explanation:
A suitable app or calculator does this easily. (Since you're asking here, you're obviously not unwilling to use technology to help.)
_____
Given two sides and the included angle, the Law of Cosines can help you find the third side.
... b² = a² + c² - 2ac·cos(B)
... b² = 38² + 18² -2·38·18·cos(36°) ≈ 661.26475
... b ≈ 25.715
Then the Law of Sines can help you find the other angles. It can work well to find the smaller angle first (the one opposite the shortest side). That way, you can tell if the larger angle is obtuse or acute.
... sin(C)/c = sin(B)/b
... C = arcsin(c/b·sin(B)) ≈ 24.29515°
This angle and angle B add to less than 90°, so the remaining angle is obtuse. (∠A can also be found as 180° - ∠B - ∠C.)
... A = arcsin(a/b·sin(B)) ≈ 119.70485°
Answer:
Step-by-step explanation:
The answer is X-(-9)+10=11