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A root of a sum of the cosine and the sine beside a half power of one of them is read in the tangent - #1858

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a-root-beside-a-half-power-of-the-cosine
Oct 12, 2026
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Rafael-SOWNet merged 6 commits into
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a-root-beside-a-half-power-of-the-cosine

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Part of #718.

csc(x) sqrt(cos(x) + sin(x))/cos(x)^(3/2) was declined, Rubi's 4.7.7 #1123, with its respellings. SolveByTangentSubstitution now reads sqrt(a cos + b sin) beside a half-odd power of the cosine as sqrt(a + b tan) times a whole power of the cosine, and the sine the same way through a/tan + b, so what is left is a function of the tangent.

The respelling is exact wherever the integrand is real: the root of a product of two non-negatives is the product of the roots, and when the sum and the cosine are both negative the two factors of i cancel. Off the real domain the answer takes the branches of the respelling.

Input 2.5.0 master a96bfa0 this branch
csc(x)*sqrt(cos(x) + sin(x))/cos(x)^(3/2) declined declined 94 characters
sqrt(cos(x) + sin(x))/cos(x)^(5/2) declined declined (1 + tan(x)) ^ (3/2) / (3/2)
sqrt(2*cos(x) + 3*sin(x))/(sin(x)*cos(x)^(3/2)) declined declined 138 characters
sec(x)*sqrt(cos(x) - sin(x))/sin(x)^(3/2) declined declined 74 characters
1/(cos(x)^(3/2)*sqrt(3*cos(x) + sin(x))) declined declined 2 * sqrt(tan(x) + 3)

Rubi corpus, branch against master's tree: one problem gained (4.7.7 #1123), none lost, 0 wrong in every family; a pocket of all of 4.7.7 gained #1122 and #1123. Kernel gate and the full suite (15261 passed) pass.

🤖 Generated with Claude Code

https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura

Rafael-SOWNet and others added 6 commits October 12, 2026 02:39
…e the other way up

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura
…ot of a + b tan

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura
…hanges

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012sonx8iAspMiwRwokT1Ura
@Rafael-SOWNet Rafael-SOWNet added this to the 2.6.0 milestone Oct 12, 2026
@Rafael-SOWNet
Rafael-SOWNet merged commit de3e6ff into master Oct 12, 2026
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Rafael-SOWNet deleted the a-root-beside-a-half-power-of-the-cosine branch October 12, 2026 11:51
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