Answer:
480
Step-by-step explanation:
Sn = n÷2 × (2a + (n-1)d)
n = 20 a = -14 d = 4
S20 = 10 × (-28 + 19 × 4) = 480
The answer to the question is 43
9514 1404 393
Answer:
47 -6√10
Step-by-step explanation:
As you know, the area of a square is the square of the side length. It can be helpful here to make use of the form for the square of a binomial.
(a -b)² = a² - 2ab + b²
(√2 -3√5)² = (√2)² - 2(√2)(3√5) + (3√5)²
= 2 - 6√10 + 3²(5)
= 47 -6√10
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<em>Check</em>
√2-3√5 ≈ -5.29399 . . . . . . . . note that a negative value for side length makes no sense, so this isn't about geometry, it's about binomials and radicals
(√2-3√5)² ≈ 28.02633
47 -6√10 ≈ 28.02633
The sum of angles of a triangle is 180°, so m∠K = 180° -45° -30° = 105°.
The Law of Sines tells you
... FL/sin(∠K) = FK/sin(∠L)
Solving for FL, we get
... FL = FK·sin(∠K)/sin(∠L)
... FL = a·sin(105°)/sin(30°) = a·sin(105°)/(1/2)
... FL = 2a·sin(105°) ≈ 1.93185a
Answer:
23 17 31
Step-by-step explanation:
igotitright