Given: △ABC, m∠A=120°, AB=AC=1 Find: The radius of circumscribed circle
1 answer:
In Δ ABC, ∠A=120°, AB=AC=1
To draw a circumscribed circle Draw perpendicular bisectors of any of two sides.The point where these bisectors meet is the center of the circle.Mark the center as O.
Then join OA, OB, and OC.
Taking any one OA,OB and OC as radius draw the circumcircle.
Now, from O Draw OM⊥AB and ON⊥AC.
As chord AB and AC are equal,So OM and ON will also be equal.
The reason being that equal chords are equidistant from the center.
AM=MB=1/2 and AN=NC=1/2 [ perpendicular from the center to the chord bisects the chord.]
In Δ OMA and ΔONA
OM=ON [proved above]
OA is common.
MA=NA=1/2 [proved above]
ΔOMA≅ ONA [SSS]
∴ ∠OAN =∠OAM=60° [ CPCT]
In Δ OAN
OA=1
∴ OA=OB=OC=1, which is the radius of given Circumscribed circle.
You might be interested in
Answer:
The confidence interval for the mean is given by the following formula:
(1)
The 90% confidence interval for this case would be (38.01, 44.29) and is given.
The best interpretation for this case would be: We are 90% confident that the true average is between $ 38.01 and $ 44.29 .
And the best option would be:
The store manager is 90% confident that the average amount spent by all customers is between S38.01 and $44.29
Step-by-step explanation:
Assuming this complete question: Which statement gives a valid interpretation of the interval?
The store manager is 90% confident that the average amount spent by the 36 sampled customers is between S38.01 and $44.29.
There is a 90% chance that the mean amount spent by all customers is between S38.01 and $44.29.
There is a 90% chance that a randomly selected customer will spend between S38.01 and $44.29.
The store manager is 90% confident that the average amount spent by all customers is between S38.01 and $44.29
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
Solution to the problem
The confidence interval for the mean is given by the following formula:
(1)
The 90% confidence interval for this case would be (38.01, 44.29) and is given.
The best interpretation for this case would be: We are 90% confident that the true average is between $ 38.01 and $ 44.29 .
And the best option would be:
The store manager is 90% confident that the average amount spent by all customers is between S38.01 and $44.29
Answer:
6.33... and 0.333...
Step-by-step explanation:
The quadratic formula is
.
It is important because while some quadratics are factorable and can be solved not all are. The formula will solve all quadratic equations and can also give both real and imaginary solutions. Using the formula will require less work than finding the factors if factorable. We will substitute a=9, b=-54 and c=-19.
We will now solve for the plus and the minus.
The plus,,,
and the minus...