From adf0d364898650994aa5db20494a33d9a9d1a4f4 Mon Sep 17 00:00:00 2001 From: James Su Date: Mon, 30 Dec 2019 03:12:05 +0000 Subject: [PATCH] Add new file --- .../Trigonometry.md | 78 +++++++++++++++++++ 1 file changed, 78 insertions(+) create mode 100644 Grade 10/Math/MPM2DZ/Math Oral Presentation Questions/Trigonometry.md diff --git a/Grade 10/Math/MPM2DZ/Math Oral Presentation Questions/Trigonometry.md b/Grade 10/Math/MPM2DZ/Math Oral Presentation Questions/Trigonometry.md new file mode 100644 index 0000000..44f1a7e --- /dev/null +++ b/Grade 10/Math/MPM2DZ/Math Oral Presentation Questions/Trigonometry.md @@ -0,0 +1,78 @@ +## Trigonometry + +### Question 1 a) + +It means to solve all missing/unknown angles and sidelengths. It can be achieved by using some of the following: + +1. Sine/cosine law +2. Primary Trigonometry Ratios +3. Similar / Congruent Triangle theorems +4. Angle Theorems +5. Pythagorean Theorem + +### Question 1 b) + +Draw a line bisector perpendiculr to $`\overline{XZ}`$. Then by using pythagorean theorem: $`7^2 - y^2 = h^2`$, where $`h`$ is the height. + +$`\therefore h = \sqrt{13} \approx 3.61cm`$ + +### Question 1 c) + +We can draw a triangle $`ABC`$ where $`\angle A`$ is the angle between the hands, and $\overline{AB}`$ and $`\overline{BC}`$ are the long and short hands respectively. + +Since a clock is a circle, $`\angle A = \dfrac{360}{12} \times 2 = 60^o`$ + +Let $`x`$ be the distance between the 2 hands. By using the law of cosines: + +$`x^2 = 12^2 + 15^2 - 2(15)(12)\cos60`$ + +$`x = 13.7cm`$. + +The distance between the 2 hands is $`13.7cm`$. + +### Question 2 a) + +Lets split the tree into the 2 triangles shown on the diagram. By using the primary trigonmetry ratios, we know that the bottom triangle's height side lenghts that is part of +the tree's height is $`100\tan 10`$, and $`100 \tan 25`$ for the top triangle. + +Therefore the tree's height is the sum of these 2 triangle's side length. + +Therefore the total height is $`100(\tan 25 + \tan 10) = 64.3`$ + +The height of the tree is $`64.3m`$ + +### Question 2 b) + +$`\angle G = 180 - 35 - 68 = 77 (ASTT) `$ + +By using the law of sines. + +$`\overline{RG} = \dfrac{173.2 \sin 35}{\sin 77} = 102m`$ + +By using the law of sines. + +$`\overline{TG} = \dfrac{173.2 \sin 68}{\sin 77} = 164.8m`$ + +$`P = 173.2 + 164.8 + 102 = 440m`$ + +The perimeter is $`440m`$ + +### Question 2 c) + +We know the buildings must be on the same side because they both cast a shadow from the same one sun. + +Let the triangle formed by the flagpole be $`\triangle FPS`$ and the one by the building $`\triangle TBS`$ + +$`\because \angle B = \angle P`$ (given) + +$`\because \angle S`$ is common. + +$`\therefore \triangle TBS \sim \triangle FPS`$ (AA similarity theorem) + +$`\dfrac{TB}{BS} = \dfrac{FP}{PS} \implies \dfrac{TB}{26} = \dfrac{25}{10]`$ + +$`\therefore TB = \dfrac{25(26)}{10} = 65`$ + +Therefore the building is $`65m`$ tall. + +### Question 3 a)