Answer: B) BC=4 in.
Step-by-step explanation:
Given: In △ABC , AB=4 inch ,AC=4 in. , and m∠A=60°
⇒ AB=AC= 4 inches
⇒ △ABC is an isosceles triangle.
⇒ m∠A=60°=m∠B [angles opposite to the equal sides of a triangle are equal]
Now by angle sum property,
m∠A+m∠B+m∠C=180°
⇒60°+60°+m∠C=180°
⇒ m∠C=180°-120°
⇒ m∠C=60°
⇒ △ABC is an equilateral triangle.
⇒ BC= 4 inches [sides of an equilateral triangles are equal]
⇒ B is the right answer.
Answer:
see below
Step-by-step explanation:
The formula for the sum of an infinite geometric series with first term a1 and common ratio r (where |r| < 1) is ...
sum = a1/(1 -r)
Applying this to the given series, we get ...
a. sum = 5/(1 -3/4) = 5/(1/4) = 20
b. sum = d/(1 -1/t) = d/((t-1)/t) = dt/(t-1)
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The derivation of the above formula is in most texts on sequences and series. In general, you write an expression for the difference of the sum (S) and the product r·S. You find all terms of the series cancel except the first and last, and the last goes to zero in the limit, because r^∞ → 0 for |r| < 1. Hence you get ...
S -rS = a1
S = a1/(1 -r)