HP 35s Manual page 3

Solving trigonometry problems

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HP 35s Solving Trigonometry Problems

Solution:

In RPN mode, calculate π/2, then press k.

¹j2¯k.

In algebraic mode, press k then calculate π/2.

k¹j¯2Ï.

Answer:

The sine of π/2 radians is calculated as exactly 1

Example 3: Show that the rule sin²(x) + cos²(x) = 1 applies correctly when x is 30°.

Solution:

First, remember to set the required angle mode. Press 91.

In algebraic mode:

º=k30ÕÕÙº=n30Ï

In RPN mode:

30kº=30nº=Ù

Answer:

Both the algebraic and the RPN calculations confirm that the rule sin²(x) + cos²(x) = 1 applies correctly

when x is 30°.

Example 4: A designer wants to use triangular tiles with sides 3 inches, 5 inches and 7 inches long, to put a mosaic on

a floor. What is the angle opposite the 7 inch side? Will it be possible to lay three tiles next to each other

with this angle pointing inwards?

Solution:

Use the cosine rule to calculate the angle. The cosine rule states that for any triangle with sides a, b and c,

and angle A facing side a:

From this, A can be calculated as:

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Figure 2

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Figure 4

Figure 5

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HP 35s Solving Trigonometry Problems - Version 1.0