Answer:
Gọi AH là đường cao kẻ từ A đến BC
Xét tam giác AHC vuông tại H
Suy ra AH = HC. cotA= 9.cot35° = 12,9
Xét tam giác AHB vuông tại H
Suy ra BH = AH.tanA = 12,9.tan61°=23,37
Ta có BC= HC+ HB= 9+23,27 =32,27
Diện tích tam giác ABC = 1/2 × AH ×BC= 1/2 ×12,9×32,27=208,1415
Correct Answer:Second option
Solution:The given sequence is:
2.2, 6.6, 11, ...
If we observe the sequence it is an Arithmetic Sequence as the difference between two consecutive terms is the same.
6.6 - 2.2 = 4.4
11 - 6.6 = 4.4
First we find the general term for this sequence.


first term = 2.2
d = 4.4
So,

This general term will be placed inside the summation sign with limits from 1 to 5 to give the sum of first 5 terms of the given sequence. So the correct answer is Second Option
Answer:
E. 396/538
Step-by-step explanation:
The probability that the senior selected will not be from High School B given that the senior did not answer colege:
First, what's the probability of not having answered college? This will be out denominator.
P(not choosing college) = 244 + 106 + 188 = 538
Next, what's the probability that a senior in that category is not from HS B? Well, add the probabilities that the senior is in HS A or C:
P(senior is in HS A or C and answered not college) = 49 + 99 + 63 + 83 + 31 + 71 = 396
<u>Our answer is E. 396/538.</u>