Respuesta :

marcthemathtutor

Answer:

8. 8.80

9. 90

Step-by-step explanation:

Question 8: Use the Pythagorean formula

DE² = DF²+EF²

EF² = DE² - DF²

= 16.2² - 13.6²

= 77.48

EF = √77.48 = 8.80  (Answer)

Question 9: Use the Cosine Rule

GI² = GH² +HI² - 2·GH·HI·Cos ∠GHI

= 60² + 42² - 2·60·42·Cos 123

= 3600 +1764 - (-2744.98)

= 8108.98

GI = √8108.98 = 90

Answer:

Step-by-step explanation:

8.

[tex]x=\sqrt{16.2^2-13.6^2} \\=\sqrt{(16.2-13.6)(16.2+13.6)} \\=\sqrt{2.6*29.8} \\=2\sqrt{1.3*14.9} \\=2\sqrt{19.37} \\\approx 8.80[/tex]

9.

2*60*42*cos 123=60²+42²-GI²

GI²=3600+1764-5040 cos 123

GI²=5364-5040 cos 123

GI=90.05 (approx)

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