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10.5 Trigonometry and Area. What is the area of a regular nonagon with 10-cm sides?. Finding Area. A stop sign is a regular octagon. The standard size has a 16.2-in. radius. What is the area of the stop sign to the nearest square inch?. Area of a Triangle Given SAS. - PowerPoint PPT Presentation
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10.5 Trigonometry and Area• What is the area of a regular nonagon with 10-cm
sides?360
409
m PCR
1(40) 202
m PCS
5tan 20
a
5
tan 20a
1
2A ap
1 590
2 tan 20A
2618 .cm
Finding Area• A stop sign is a regular octagon. The standard size
has a 16.2-in. radius. What is the area of the stop sign to the nearest square inch?
36045
8
22.5m C cos22.5
16.2
a
16.2(cos22.5 ) a
sin 22.516.2
x
16(sin 22.5 ) x
8 2p x 8 2 16.2(sin 22.5 )p
259.2(sin 22.5 )
1
2A ap
116.2(cos22.5) 259.2(sin 22.5)
2
742.29241462742 .in
Area of a Triangle Given SAS
• The area of a triangle is half the product of the lengths of two sides and the sine of the included angle.
1(sin )
2Areaof ABC bc A
Finding Area• What is the area of the triangle?
112 21 sin 48
2A
93.63624801294 .cm
More Practice!!!!!
• Homework – Textbook p. 646 #6 – 18 EVEN.
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