Bán kính đường tròn ngoại tiếp tam giác ABC bằng: A. 3105 B. 255 C. 2105 D. 355

Đáp án đúng là A Phương pháp giải Tính diện tích tam giác để tính bán kính đường tròn ngoại tiếp. Lời giải AB→=1;−1;2,AC→=−2;1;1,BC→=−3;2;−1 AB=AC=6,BC=14 AB→,AC→=−3;−5;−1⇒SΔABC=12AB→,AC→=352 Mà ta có: SΔABC=AB.BC.CA4.RΔABC⇒RΔABC=AB.BC.CA4.SΔABC=3105

Câu hỏi:

23/02/2025 60

Bán kính đường tròn ngoại tiếp tam giác ABC bằng:

A. $\frac{3 \sqrt{10}}{5}$

Đáp án chính xác

B. $\frac{2 \sqrt{5}}{5}$

C. $\frac{2 \sqrt{10}}{5}$

D. $\frac{3 \sqrt{5}}{5}$

Xem lời giải

Câu hỏi trong đề: (2025) Đề thi thử Đánh giá năng lực ĐHQG Hồ Chí Minh năm 2025 có đáp án (Đề 3) !!

Trả lời:

Giải bởi Vietjack

Đáp án đúng là A

Phương pháp giải

Tính diện tích tam giác để tính bán kính đường tròn ngoại tiếp.

Lời giải

$\vec{AB} = (1; - 1; 2), \vec{AC} = (- 2; 1; 1), \vec{BC} = (- 3; 2; - 1)$

$AB = AC = \sqrt{6}, BC = \sqrt{14}$

$[\vec{AB}, \vec{AC}] = (- 3; - 5; - 1) \Rightarrow S_{ΔABC} = \frac{1}{2} |[\vec{AB}, \vec{AC}]| = \frac{\sqrt{35}}{2}$

Mà ta có: $S_{ΔABC} = \frac{AB . BC . CA}{4 . R_{ΔABC}} \Rightarrow R_{ΔABC} = \frac{AB . BC . CA}{4 . S_{ΔABC}} = \frac{3 \sqrt{10}}{5}$

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Xem thêm các câu hỏi khác »

Bán kính đường tròn ngoại tiếp tam giác ABC bằng:

Nhà sách VIETJACK:

It’s not the sort of show you’d watch from start to finish, but it’s fun to _____ every now and then.

Which of the following best serves as a title for the passage?

What could be the best title for the passage?

Lisa: There is a music concert next weekend. – John: That sounds great! Who __________ there?

The student’s efforts were commendable, but they still struggled with the final exam.

Handcrafted pottery from Mexico, paired with vintage lamps, have made Jason’s apartment the center of attention at the party.

Which of the following best restates each of the given sentences?

Despite his initial reluctance, John eventually embraced the new project.

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Bán kính đường tròn ngoại tiếp tam giác ABC bằng:

Nhà sách VIETJACK:

It’s not the sort of show you’d watch from start to finish, but it’s fun to _____ every now and then.

Which of the following best serves as a title for the passage?

What could be the best title for the passage?

Lisa: There is a music concert next weekend. – John: That sounds great! Who __________ there?

The student’s efforts were commendable, but they still struggled with the final exam.

Handcrafted pottery from Mexico, paired with vintage lamps, have made Jason’s apartment the center of attention at the party.

Which of the following best restates each of the given sentences? Despite his initial reluctance, John eventually embraced the new project.

Bình luận

🔥 Đề thi HOT:

VIP +3 tháng ( 199,000 VNĐ )

VIP +6 tháng ( 299,000 VNĐ )

VIP +12 tháng ( 499,000 VNĐ )

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Which of the following best restates each of the given sentences?

Despite his initial reluctance, John eventually embraced the new project.