Cho hình chóp đều <span class="MathJax_Preview" style="color: inherit;"><span class="MJXp-math" id="MJXp-Span-1"><span class="MJXp-mstyle" id="MJXp-Span-2"><span class="MJXp-mi MJXp-italic" id="MJXp-Span-3">S</span><span class="MJXp-mo" id="MJXp-Span-4" style="margin-left: 0em; margin-right: 0.222em;">.</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-5">A</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-6">B</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-7">C</span></span></span></span><span id="MathJax-Element-1-Frame" class="mjx-chtml MathJax_CHTML MJXc-processed" tabindex="0" style="font-size: 127%;"><span id="MJXc-Node-1" class="mjx-math"><span id="MJXc-Node-2" class="mjx-mrow"><span id="MJXc-Node-3" class="mjx-mstyle"><span id="MJXc-Node-4" class="mjx-mrow" style="font-size: 120%;"><span id="MJXc-Node-5" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.495em; padding-bottom: 0.298em; padding-right: 0.032em;">S</span></span><span id="MJXc-Node-6" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R" style="margin-top: -0.145em; padding-bottom: 0.347em;">.</span></span><span id="MJXc-Node-7" class="mjx-mi MJXc-space1"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.495em; padding-bottom: 0.298em;">A</span></span><span id="MJXc-Node-8" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.445em; padding-bottom: 0.298em;">B</span></span><span id="MJXc-Node-9" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.495em; padding-bottom: 0.298em; padding-right: 0.045em;">C</span></span></span></span></span></span></span><script type="math/tex" id="MathJax-Element-1">\large S.ABC</script> có <span class="MathJax_Preview" style="color: inherit;"><span class="MJXp-math" id="MJXp-Span-8"><span class="MJXp-mstyle" id="MJXp-Span-9"><span class="MJXp-mi MJXp-italic" id="MJXp-Span-10">S</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-11">A</span><span class="MJXp-mo" id="MJXp-Span-12" style="margin-left: 0.333em; margin-right: 0.333em;">=</span><span class="MJXp-mn" id="MJXp-Span-13">2</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-14">a</span><span class="MJXp-mo" id="MJXp-Span-15" style="margin-left: 0em; margin-right: 0.222em;">,</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-16">A</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-17">B</span><span class="MJXp-mo" id="MJXp-Span-18" style="margin-left: 0.333em; margin-right: 0.333em;">=</span><span class="MJXp-mn" id="MJXp-Span-19">3</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-20">a</span></span></span></span><span id="MathJax-Element-2-Frame" class="mjx-chtml MathJax_CHTML MJXc-processed" tabindex="0" style="font-size: 127%;"><span id="MJXc-Node-10" class="mjx-math"><span id="MJXc-Node-11" class="mjx-mrow"><span id="MJXc-Node-12" class="mjx-mstyle"><span id="MJXc-Node-13" class="mjx-mrow" style="font-size: 120%;"><span id="MJXc-Node-14" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.495em; padding-bottom: 0.298em; padding-right: 0.032em;">S</span></span><span id="MJXc-Node-15" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.495em; padding-bottom: 0.298em;">A</span></span><span id="MJXc-Node-16" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.101em; padding-bottom: 0.298em;">=</span></span><span id="MJXc-Node-17" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">2</span></span><span id="MJXc-Node-18" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.199em; padding-bottom: 0.298em;">a</span></span><span id="MJXc-Node-19" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R" style="margin-top: -0.145em; padding-bottom: 0.544em;">,</span></span><span id="MJXc-Node-20" class="mjx-mi MJXc-space1"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.495em; padding-bottom: 0.298em;">A</span></span><span id="MJXc-Node-21" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.445em; padding-bottom: 0.298em;">B</span></span><span id="MJXc-Node-22" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.101em; padding-bottom: 0.298em;">=</span></span><span id="MJXc-Node-23" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">3</span></span><span id="MJXc-Node-24" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.199em; padding-bottom: 0.298em;">a</span></span></span></span></span></span></span><script type="math/tex" id="MathJax-Element-2">\large SA= 2a, AB= 3a</script>. Tính tan

Cho hình chóp đều S.ABCS.ABCSA=2a,AB=3aSA=2a,AB=3a. Tính tan

4/5

Tác giả: Thầy Tùng

Đăng ngày: 19 Aug 2022

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Hình minh họa Cho hình chóp đều $\large S.ABC$ có $\large SA= 2a, AB= 3a$. Tính tan

Câu hỏi:

Cho hình chóp đều S.ABCS.ABCSA=2a,AB=3aSA=2a,AB=3a. Tính tan của góc tạo bởi hai mặt phẳng (SBC)(SBC)(ABC)(ABC)

Đáp án án đúng là: D

Lời giải chi tiết:

Hình đáp án 1. Cho hình chóp đều $\large S.ABC$ có $\large SA= 2a, AB= 3a$. Tính tan

Gọi I là trọng tâm của tam giác ABC

Ta có: AH=23AI=23.3a32=a3AH=23AI=23.3a32=a3

Ta có: HIBC(^(SBC),(ABC))=^(SI,AI)=^(SIA)HIBC(ˆ(SBC),(ABC))=ˆ(SI,AI)=ˆ(SIA)

Ta có: {SH=SA2AH2=(2a)2(a3)2HI=AH2=a32 tan^SIA=SHIH=aa32=233

Đáp án D