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In the given figure, ∠B = 60°, ∠C = 30°, AB = 8 cm and BC = 24 cm. Find: a. BE b. AC - Mathematics

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Question

In the given figure, ∠B = 60°, ∠C = 30°, AB = 8 cm and BC = 24 cm. Find:
a. BE
b. AC

Sum

Solution


a. In right ΔAEB,

sin60° = `"AE"/"AB"`

⇒ `sqrt(3)/(2) = "AE"/(8)`
⇒ AE = `4sqrt(3)"cm"`
Now,
BE2 
= AB2 - AE2
= `8^2 - (4sqrt(3))^2`
= 64 - 48
= 16
⇒ BE = 4cm
b. EC
= BC - BE
= 24 - 4
= 20cm
Now,
In right ΔAEC,
AC2
= AE2 + EC2
= `(4sqrt(3))^2 + 20^2`
= 48 + 400
= 448
⇒ AC = `8sqrt(7)"cm"`.

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Trigonometric Equation Problem and Solution
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Chapter 27: Trigonometrical Ratios of Standard Angles - Exercise 27.2

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Frank Mathematics [English] Class 9 ICSE
Chapter 27 Trigonometrical Ratios of Standard Angles
Exercise 27.2 | Q 7
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