HP 33S Manual page 3

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HP 33S Solving Simple Trigonometry Problems
Example 2: What is the sine of π/2 radians?
Solution: In RPN mode, calculate π/2, then press k.
ºj2¯k.
In algebraic mode calculate π/2 in parentheses, then press k.
ºyºj¯2º|k. Following this with Ï is not necessary, but it completes the
calculation by putting an equals sign at the end.
Answer: The sine of π/2 radians is calculated as exactly 1. Answers will not always be exact as in this case. The
HP 33S works with 12 decimal digits, so trigonometric calculations can be expected to be accurate to 12
decimal places. For example the sine of π radians is calculated as 2×10
correctly equal to zero to 12 decimal places.
Example 3: Show that the rule sin²(x) + cos²(x) = 1 applies correctly when x is 45°.
Solution: First, remember to set the required angle mode. Press Ý1.
In algebraic mode, work through the problem by calculating the sine, squaring it, then adding the square of
the cosine:
45k=Ù45n=Ï
The same can be done in RPN mode. First, calculate the sine and cosine of 45°. Then add:
45Ïk=wn=Ù
Answer: Both the algebraic and the RPN calculations confirm that the rule sin²(x) + cos²(x) = 1 applies correctly
when x is 45°.
hp calculators - 3 - HP 33S Solving Simple Trigonometry Problems - Version 1.0
Figure 3
, displayed as 2E-13, which is
-13
Figure 4
Figure 5