Question

If cos x = sin(20 + x) ° and 0°

Answer 1

x = 35°

Explanation:

The question is as following

cos x = sin(20 + x)° and 0° < x < 90° , find X?

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cos x = sin(20 + x)°

sin and cos are co-functions,

which means that: cos x = cos [90 - (20 + x)]

∴ x = 70 - x

∴ 2x = 70

∴ x = 35°

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Note: cos θ = sin ( 90 - θ )

Answer 2

x = 35°

Explanation:

The question is as following

cos x = sin(20 + x)° and 0° < x < 90° , find X?

==============================================

cos x = sin(20 + x)°

sin and cos are co-functions,

which means that: cos x = cos [90 - (20 + x)]

∴ x = 70 - x

∴ 2x = 70

∴ x = 35°

======================

Note: cos θ = sin ( 90 - θ )