# Date: 2/7 Aim: To use trigonometric ratios for indirect measurements of right triangles.

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Date: 2/7 Aim: To use trigonometric ratios for indirect measurements of right triangles.

Trigonometry Derived from Greek words, “trigonon" which means triangle, and "metria” which means measure.Derived from Greek words, “trigonon" which means triangle, and "metria” which means measure. Trigonon metria = “triangle measurement” Trigonon metria = “triangle measurement” Sine - comes from the Latin word sinus meaning a curve or fold. Cosine - was originally written "co.sine," short for COMPLEMENTI SINUS: the sine of the complementary angle. Tangent - comes from the Latin word tangens which is a straight line which touches a circle at one point.

Triangle Ratios

SOH CAH TOA is mnemonic for: SOH CAH TOA

Trigonometry C A B a b c

Using Trigonometry B C A 29 c a

tan 32 o = opp. adj. tan 32 o 11 = x x tan 32 o = 11 x = 11 tan 32 o x 11 0.6249 x 17.6 Try on your own: y

A 20-ft wire supporting a flagpole forms a 35 o angle with the flagpole. To the nearest foot, how high is the flagpole? 20 x Using Trigonometry

You want to build a skateboard ramp with a length of 14 feet and an angle of elevation of 26°. You need to find the height and length of the base of the ramp. sin 26 o = opp. hyp. sin 26 o x = 14 14 sin 26 o = x 6.1 ft. x cos 26 o = adj. hyp. cos 26 o y = 14 14 cos 26 o = y 12.6 ft. y

Date: 2/8 Aim: To use these ratios for indirect measurements of right triangles. Do Now: Find h.

Find the height h of the lamppost to the nearest inch. tan 70 o = opp. adj. tan 70 o h = 40 40 tan 70 o = h 109.9 h ANSWER The lamppost is about 110 inches tall.

Mount Everest – 29, 029 feet

The Burj Khalifa, Dubai – 2717 feet

Angel, Salto – Venezuela - 3,212 feet

Clinometer

42 ° Angle of Elevation Angle of Depression 42 °

The angle of elevation of an object as seen by an observer is the angle between the horizontal and the line from the object to the observer's eye (the line of sight). If the object is below the level of the observer, then the angle between the horizontal and the observer's line of sight is called the angle of depression.

A - angle of elevation A θ B B – angle of depression θ – angle of interest Which angle is the angle of elevation? Which angle is the angle of depression ?

Exact Answer: 1,250 feet tall How tall is the Empire State Building? 76.5° 300 ft

Since Mount Everest is 29, 029 feet tall, how far was Ms. Psillos from the mountain, if her angle of elevation was 55°? 20,326.3 feet

Ms. Psillos is looking up at the waterfall in Angel, Salto – Venezuela, which is 3,212 feet tall, and has an angle of elevation of 82°. She wants to know the distance that her line of sight makes to the top of the waterfall? 3,243.6 feet

Using Trigonometry ST R 41 47

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